False positive 'attribute-allowed-values' in case of uppercase enumerated html attributes.

Reduced test-case

test.html

<html lang="en">
	<head>
		<title>title</title>
	</head>
	<body>
		<form method="POST">
			<input type="text">
		</form>
	</body>
</html>

Configuration

.htmlvalidate.json

{
  "extends": [
    "html-validate:recommended"
  ],

  "rules": {
    "attribute-boolean-style": "off",
    "attribute-allowed-values": "error",
    "no-trailing-whitespace": "off",
    "no-inline-style": "off",
    "wcag/h30": "off",
    "wcag/h32": "off",
    "wcag/h36": "off",
    "wcag/h37": "off",
    "wcag/h67": "off",
    "wcag/h71": "off"
  }
}

Expected result

Based on this the validation completes without any error.

Actual result

html-validate test.html reports error like below:

  6:17  error  Attribute "method" has invalid value "POST"  attribute-allowed-values

✖ 1 problem (1 error, 0 warnings)

More information:
  https://html-validate.org/rules/attribute-allowed-values.html

Version

html-validate: 7.0.0

Workaround

Adding the lines below to .htmlvalidate.json to avoid errors in test case mentioned above.

{
...,
  
  "elements": [
    "html5",
    {
      "form": {
        "attributes": {
          "method": [ "get", "post", "GET", "POST" ]
        }
      }
    }
  ]
}