Bump NUnit from 3.14.0 to 4.0.1

Bumps [NUnit](https://github.com/nunit/nunit) from 3.14.0 to 4.0.1.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/master/CHANGES.md)
- [Commits](nunit/nunit@v3.14.0...v4.0.1)

---
updated-dependencies:
- dependency-name: NUnit
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

PropertyChangedAnalyzers.Benchmarks/PropertyChangedAnalyzers.Benchmarks.csproj

@@ -22,7 +22,7 @@
     <PackageReference Include="Gu.Roslyn.Asserts" Version="4.3.0" />
     <PackageReference Include="IDisposableAnalyzers" Version="4.0.7" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.5.0" />
-    <PackageReference Include="NUnit" Version="3.14.0" />
+    <PackageReference Include="NUnit" Version="4.0.1" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" PrivateAssets="all" />
     <PackageReference Include="ReflectionAnalyzers" Version="0.3.1" PrivateAssets="all" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.507" PrivateAssets="all" />