Bump the mstest group across 1 directory with 2 updates (#136)

Bumps the mstest group with 2 updates in the /test/WebExtensions.Net.IntegrationTestsRunner directory: [MSTest.TestAdapter](https://github.com/microsoft/testfx) and [MSTest.TestFramework](https://github.com/microsoft/testfx).


Updates `MSTest.TestAdapter` from 3.7.3 to 3.8.2
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.7.3...v3.8.2)

Updates `MSTest.TestFramework` from 3.7.3 to 3.8.2
- [Release notes](https://github.com/microsoft/testfx/releases)
- [Changelog](https://github.com/microsoft/testfx/blob/main/docs/Changelog.md)
- [Commits](microsoft/testfx@v3.7.3...v3.8.2)

---
updated-dependencies:
- dependency-name: MSTest.TestAdapter
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: mstest
- dependency-name: MSTest.TestFramework
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: mstest
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

test/WebExtensions.Net.IntegrationTestsRunner/WebExtensions.Net.IntegrationTestsRunner.csproj

@@ -9,8 +9,8 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="Microsoft.Playwright" Version="1.51.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="3.7.3" />
-    <PackageReference Include="MSTest.TestFramework" Version="3.7.3" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.9.1" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.9.1" />
     <PackageReference Include="System.Xml.XmlSerializer" Version="4.3.0" />
   </ItemGroup>