Bump the tests group across 1 directory with 2 updates

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


Updates `MSTest.TestAdapter` from 3.7.0 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@v3.7.0...v3.7.3)

Updates `MSTest.TestFramework` from 3.7.0 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@v3.7.0...v3.7.3)

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

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

Author: dependabot[bot]

src/iTextSharp.LGPLv2.Core.FunctionalTests/iTextSharp.LGPLv2.Core.FunctionalTests.csproj

@@ -23,8 +23,8 @@
     </ItemGroup>
     <ItemGroup>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0"/>
-        <PackageReference Include="MSTest.TestAdapter" Version="3.7.0"/>
-        <PackageReference Include="MSTest.TestFramework" Version="3.7.0"/>
+        <PackageReference Include="MSTest.TestAdapter" Version="3.7.3"/>
+        <PackageReference Include="MSTest.TestFramework" Version="3.7.3"/>
 
         <PackageReference Include="BitMiracle.LibTiff.NET" Version="2.4.660"/>
     </ItemGroup>