Bump NUnit3TestAdapter from 4.1.0 to 4.2.0 (#51)

Bumps [NUnit3TestAdapter](https://github.com/nunit/nunit3-vs-adapter) from 4.1.0 to 4.2.0.
- [Release notes](https://github.com/nunit/nunit3-vs-adapter/releases)
- [Commits](nunit/nunit3-vs-adapter@V4.1.0...V4.2.0)

---
updated-dependencies:
- dependency-name: NUnit3TestAdapter
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

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

RegexToolbox.Tests/RegexToolbox.Tests.csproj

@@ -11,7 +11,7 @@
  <ItemGroup>
  <PackageReference Include="NSubstitute" Version="4.2.2" />
  <PackageReference Include="nunit" Version="3.13.2" />
- <PackageReference Include="NUnit3TestAdapter" Version="4.1.0" />
+ <PackageReference Include="NUnit3TestAdapter" Version="4.2.0" />
  <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.0.0" />
  </ItemGroup>