build(deps): bump MSTest.TestAdapter from 3.6.3 to 3.6.4

Bumps [MSTest.TestAdapter](https://github.com/microsoft/testfx) from 3.6.3 to 3.6.4.
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.6.3...v3.6.4)

---
updated-dependencies:
- dependency-name: MSTest.TestAdapter
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Directory.Packages.props

@@ -13,7 +13,7 @@
   <!-- ServiceFabric.Mocks.NetCoreTests.csproj -->
   <ItemGroup>
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
-    <PackageVersion Include="MSTest.TestAdapter" Version="3.6.3" />
+    <PackageVersion Include="MSTest.TestAdapter" Version="3.6.4" />
     <PackageVersion Include="MSTest.TestFramework" Version="3.6.4" />
   </ItemGroup>