chore: Update validate-pr workflow

[stephanie-anderson]

Update validate-pr action to getsentry/github-workflows@71588dd.

Changes included:

• Skip all checks when a maintainer reopens a PR (feat(validate-pr): Skip all checks when a maintainer reopens a PR github-workflows#161)
• Skip checks for users with write access (feat(validate-pr): Skip checks for users with write access github-workflows#162)

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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Internal Changes 🔧

• Update validate-pr workflow by stephanie-anderson in #1198

• Pin GitHub Actions to full-length commit SHAs by joshuarli in #1180

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