v0.8.0 Security hardening and more unit-tests

What's Changed

• Add php version sniff by @ylebre in #22
• Add php linter by @ylebre in #21
• Fix yaml syntax by @ylebre in #23
• Feature/phpunit workflow by @ylebre in #24
• added tests for validateDPOP, fixed some validations by @poef in #26
• Add JTI validation by @Potherca in #28

New Contributors

• @poef made their first contribution in #26

Full Changelog: v0.7.0...v0.8.0