Update guzzlehttp/guzzle requirement from ^6.3 to ^6.3 || ^7.0

Updates the requirements on guzzlehttp/guzzle to permit the latest version.

Release notes

Sourced from guzzlehttp/guzzle's releases.

Release 7.2.0

See change log for changes.

Changelog

Sourced from guzzlehttp/guzzle's changelog.

7.2.0 - 2020-10-10

Added

• Support for PHP 8 #2712, #2715, #2789
• Support passing a body summarizer to the http errors middleware #2795

Fixed

• Handle exceptions during response creation #2591
• Fix CURLOPT_ENCODING not to be overwritten #2595
• Make sure the Request always has a body object #2804

Changed

• The TooManyRedirectsException has a response #2660
• Avoid "functions" from dependencies #2712

Deprecated

• Using environment variable GUZZLE_CURL_SELECT_TIMEOUT #2786

7.1.1 - 2020-09-30

Fixed

• Incorrect EOF detection for response body streams on Windows.

Changed

• We dont connect curl sink on HEAD requests.
• Removed some PHP 5 workarounds

7.1.0 - 2020-09-22

Added

• GuzzleHttp\MessageFormatterInterface

Fixed

• Fixed issue that caused cookies with no value not to be stored.
• On redirects, we allow all safe methods like GET, HEAD and OPTIONS.
• Fixed logging on empty responses.
• Make sure MessageFormatter::format returns string

Deprecated

• All functions in GuzzleHttp has been deprecated. Use static methods on Utils instead.
• ClientInterface::getConfig()

... (truncated)

Commits

• 0aa74df Release 7.2.0 (#2808)
• 368bf4d Fix CURLOPT_ENCODING not to be overwritten (#2595)
• 957b0a0 Support setting truncateBodyAt param in the http errors middleware (#2795)
• c8c99e3 Adding some highly opinionated CS fixes (#2797)
• 8d850e6 Upgrade to phpstan 0.12.48 (#2794)
• 17428d7 Merge pull request #2804 from Nyholm/head-request-fix
• d48af55 Make sure the request always has a body object.
• 3d87fb8 Fix handling of HEAD requests with Accept-Encoding header
• c3927bc Add psalm xml files to export-ignore (#2802)
• d5a2b03 Added changelog for 7.2 (#2792)
• Additional commits viewable in compare view