Bump MSTest from 3.7.2 to 3.7.3

Bumps [MSTest](https://github.com/microsoft/testfx) from 3.7.2 to 3.7.3.
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.7.2...v3.7.3)

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

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

Protocol.GeneratorTests/Protocol.GeneratorTests.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="MSTest" Version="3.7.2" />
+    <PackageReference Include="MSTest" Version="3.7.3" />
     <PackageReference Include="coverlet.collector" Version="6.0.2">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

ProtocolTests/ProtocolTests.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="FluentAssertions" Version="7.0.0" />
-    <PackageReference Include="MSTest" Version="3.7.2" />
+    <PackageReference Include="MSTest" Version="3.7.3" />
     <PackageReference Include="coverlet.collector" Version="6.0.2">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>