Add PHP 8.3 to CI actions

[vjik]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌

[what-the-diff]

PR Summary

• Removed "Fixed issues" section from PR Template
  The template used to create a new pull request on GitHub no longer contains a "Fixed issues" section. This could make the process of submitting PRs smoother, as developers won't need to fill in this section anymore.

• Increased open pull requests limit
  The open pull requests threshold for GitHub Actions has been raised in the CI/CD pipeline settings (dependabot.yml), allowing more simultaneous PRs to be processed.

• Updated Workflow with Latest PHP Versions and File Ignore
  Multiple workflow files including bc.yml, build.yml, composer-require-checker.yml, mutation.yml, rector.yml, static.yml have been updated. They now work with newer PHP versions (8.1, 8.2, and 8.3), ensuring that our code maintains compatibility with these updated versions. Additionally, certain files have been marked to be ignored in the push and pull_request triggers, which can help us focus on the most impactful changes.