PHP8.2 incompatibilities
In PHP8.2, dollar brace string interpolation is deprecated. For the RFC see https://wiki.php.net/rfc/deprecate_dollar_brace_string_interpolation
Thus php-ml is triggering E_DEPRECATED errors.
Unfortunately due to #11 I cannot fix this myself, but quoting the git version of [PHPCompatibility scanner](https://github.com/PHPCompatibility/PHPCompatibility):
```
hans@DESKTOP-EE15SLU:~/projects/PHPCompatibility$ ./vendor/bin/phpcs -p ../php-ml --standard=PHPCompatibility
............................................................ 60 / 241 (25%)
..........................................W...W.......W..... 120 / 241 (50%)
............................................................ 180 / 241 (75%)
..........W.....................W..........................W 240 / 241 (100%)
W 241 / 241 (100%)
FILE: /php-ml/src/Classification/DecisionTree.php
-----------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
-----------------------------------------------------------------------------------------------------------
389 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${median}
391 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${median}
-----------------------------------------------------------------------------------------------------------
FILE: /php-ml/src/Classification/Linear/DecisionStump.php
--------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 1 LINE
--------------------------------------------------------------------------------------------------------
90 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${this}
90 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${this}
90 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${this}
--------------------------------------------------------------------------------------------------------
FILE: /php-ml/src/Classification/DecisionTree/DecisionTreeLeaf.php
----------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 5 WARNINGS AFFECTING 4 LINES
----------------------------------------------------------------------------------------------------------
125 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${this}
135 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${value}
138 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${col}
138 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${value}
141 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${value}
----------------------------------------------------------------------------------------------------------
FILE: /php-ml/src/FeatureExtraction/StopWords.php
------------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
------------------------------------------------------------------------------------------------------------
28 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${language}
------------------------------------------------------------------------------------------------------------
FILE: /php-ml/src/Helper/OneVsRest.php
----------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
----------------------------------------------------------------------------------------------------------
160 | WARNING | Using ${var} in strings is deprecated since PHP 8.2, use {$var} instead. Found: ${label}
----------------------------------------------------------------------------------------------------------
FILE: /php-ml/trap/trap.php
--------------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
--------------------------------------------------------------------------------------------------------------
5 | WARNING | Using ${v} (variable variables) in strings is deprecated since PHP 8.2, use {${expr}} instead.
--------------------------------------------------------------------------------------------------------------
FILE: /php-ml/trap.php
--------------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
--------------------------------------------------------------------------------------------------------------
5 | WARNING | Using ${v} (variable variables) in strings is deprecated since PHP 8.2, use {${expr}} instead.
--------------------------------------------------------------------------------------------------------------
```
issue