Release v6.1.2

What's Changed

• Updated GitHub relevant files by @BitcoinMitchell in #100
• Update dependencies.yml by @BitcoinMitchell in #106
• Bump actions/cache from 3 to 4 in /.github/workflows by @dependabot in #104
• Bump actions/checkout from 2 to 4 in /.github/workflows by @dependabot in #102
• [Core] Lock Symfony to 4.4.* by @BitcoinMitchell in #107
• [Core] Ensure relevant polyfills are replaced by @BitcoinMitchell in #108
• Update README.md by @BitcoinMitchell in #109
• Initial commits for module validation by @BitcoinMitchell in #98

Full Changelog: v6.1.1...v6.1.2