Bump FluentValidation from 11.3.0 to 12.1.1 - #19

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Possible null reference argument for parameter 'source' in 'IEnumerable<Guid> Enumerable.Select<MatchmakingAssignment, Guid>(IEnumerable<MatchmakingAssignment> source, Func<MatchmakingAssignment, Guid> selector)'.

'NpgsqlEntityTypeBuilderExtensions.UseXminAsConcurrencyToken<TEntity>(EntityTypeBuilder<TEntity>)' is obsolete: 'Use EF Core's standard IsRowVersion() or

Filter expression is a constant 'true', consider removing the filter

Possible null reference argument for parameter 'source' in 'IEnumerable<Guid> Enumerable.Select<MatchmakingAssignment, Guid>(IEnumerable<MatchmakingAssignment> source, Func<MatchmakingAssignment, Guid> selector)'.

'NpgsqlEntityTypeBuilderExtensions.UseXminAsConcurrencyToken<TEntity>(EntityTypeBuilder<TEntity>)' is obsolete: 'Use EF Core's standard IsRowVersion() or

Filter expression is a constant 'true', consider removing the filter