Revert auto-merged Roslyn bumps (maintainer policy) #135

Maintainer policy: Roslyn (Microsoft.CodeAnalysis*) dependencies must never be auto-bumped. An aggregated bump auto-merged the following Roslyn updates; please revert them.

Open a PR that ONLY restores these packages to these exact versions:

• Microsoft.CodeAnalysis.CSharp.Analyzer.Testing 1.1.4 → 1.1.3 (src/StructId.Tests/StructId.Tests.csproj)

Constraints:

• Change only the version attributes listed above. No other package changes.
• Do NOT modify any .github/dependabot.yml (the ignore rule lives in devlooped/oss).
• Do NOT edit product code, tests, or any other files.
• If restoring a version breaks the build because code now depends on the newer API, stop and explain the failure in the PR description instead of changing code.