Upgrade Rails to 8.1.2 and modernize config

**Metr Tracking Issue**

**Category**: version_bump
**Commits**: 1
**Lines changed**: 383 (+185/-198)
**Time span**: 0 hours

**PRs**:
- #703 - Upgrade Rails to 8.1.2 and modernize config

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<summary>Commit details</summary>

- `0d87508` Upgrade Rails to 8.1.2 and modernize config (#703) (+185/-198)

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