Bump Shouldly from 4.2.0 to 4.2.1 in /src

Bumps [Shouldly](https://github.com/shouldly/shouldly) from 4.2.0 to 4.2.1.
- [Release notes](https://github.com/shouldly/shouldly/releases)
- [Changelog](https://github.com/shouldly/shouldly/blob/master/BREAKING%20CHANGES.txt)
- [Commits](shouldly/shouldly@4.2.0...4.2.1)

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

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

src/TfsUrlParser.Tests/TfsUrlParser.Tests.csproj

@@ -22,7 +22,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Shouldly" Version="4.2.0" />
+    <PackageReference Include="Shouldly" Version="4.2.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
     <PackageReference Include="xunit" Version="2.4.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">