Update tests (#74)

* chore: migrate CI from Travis/ORCA to GitHub Actions

Travis CI has been unused for this project for years and the "ORCA CI"
workflow was really just a Travis translation, carrying an obsolete
PHP 7.3/8.0 and Symfony 4.4/5.3 matrix.

Replace both with a single .github/workflows/tests.yml:

- Triggers on push and pull_request.
- Matrix over PHP 7.4 (the composer.json floor), 8.4 (current) and 8.5
  (next, non-blocking via continue-on-error while tooling catches up).
- Validates composer.json, installs dependencies and runs the native
  PHPUnit suite directly rather than going through make/ORCA.
- Coding standards (php-cs-fixer, phpmd) run once in a separate job on
  the current PHP version.

Also swap the Travis badge in README.md for the Actions badge and ignore
the modern .php-cs-fixer.cache filename.

* chore: pin the Tests badge to master and document the experimental PHP slot

The badge now reports the default branch explicitly rather than whichever
branch ran most recently.

The non-blocking PHP 8.5 job is a permanent slot for the next PHP release,
not a temporary hedge, so keep continue-on-error in place and promote the
version through the matrix as releases land.

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Co-authored-by: Jakob Perry <japerry@users.noreply.github.com>

Allow http-hmac-php work with psr/http-message 1 and 2.

Support for PHP8, Symfony 4.4 and 5.3, Drop support for PHP 7.2 and b…

…elow.

* Allow php8 in composer.json (fixes #57)

* Apply feedback

* update travis, drop 7.2

* drop more things

* fix travis

* Use isMainRequest and add backwards compatibility for isMasterRequest.

* Don't enforce deprecations when testing 5.3

* Fix method exists.

* Update CS fixer, use matrix for failing 4.4 on php 8.

* Correct use of matrix.

* Updates to PHP CS Fixer config.

* php fixer fixes.

* Fix a space

Co-authored-by: Jakob Perry <japerry007@gmail.com>

Update dependencies to support PHP 7.4 (#56)

Revert "Revert "Update diactoros to support Drupal 8.6+. (#52)" (#53)… (

#54)

* Revert "Revert "Update diactoros to support Drupal 8.6+. (#52)" (#53)" And keep 5.6 support.

This reverts commit 0646e4a.

* Add back testing for PHP 5.6

Revert "Update diactoros to support Drupal 8.6+. (#52)" (#53)

Update diactoros to support Drupal 8.6+. (#52)

* Update diactoros to support Drupal 8.6+.
* Reverse the if statements for Diactoros.
* Update to php 7.3, fix some linting.

Switch to PHP-CS-Fixer (#45)