Update GitHub Actions checkout version from v2 to v3

[Vikt0rPavlik]

Reason for Changes

• actions/checkout@v2 is being phased out
• v3 provides better performance and security
• Recommended to keep GitHub Actions up to date
• Better integration with GitHub's newer features
• Improved token handling

Impact

This maintenance update improves workflow security and reliability without changing functionality. The change is backward compatible and poses no risk to existing processes.

[github-actions]

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[dune-eng]

Found illegally edited file matching .github/ edited in commit: .github/workflows/prices_check.yml
Closing PR.

[dune-eng]

Found illegally edited file matching .github/ edited in commit: .github/workflows/prices_check.yml
Closing PR.