Bump System.Collections.Immutable from 8.0.0 to 10.0.8

---
updated-dependencies:
- dependency-name: System.Collections.Immutable
  dependency-version: 10.0.8
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

src/Directory.Packages.props

@@ -14,7 +14,7 @@
     <PackageVersion Include="System.Memory" Version="4.6.3" />
     <PackageVersion Include="Microsoft.Sbom.Targets" Version="4.1.5" />
     <!-- Keep at 8 to support old frameworks -->
-    <PackageVersion Include="System.Collections.Immutable" Version="8.0.0" Pinned="true" />
+    <PackageVersion Include="System.Collections.Immutable" Version="10.0.8" Pinned="true" />
     <PackageVersion Include="System.ValueTuple" Version="4.5.0" Pinned="true" />
     <PackageVersion Include="Verify" Version="31.16.3" />
   </ItemGroup>