Bump coverlet.msbuild from 3.2.0 to 6.0.0 (#275)

Bumps [coverlet.msbuild](https://github.com/coverlet-coverage/coverlet) from 3.2.0 to 6.0.0.
- [Release notes](https://github.com/coverlet-coverage/coverlet/releases)
- [Commits](coverlet-coverage/coverlet@v3.2.0...v6.0.0)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Steve Smith <steve@kentsmiths.com>

test/GuardClauses.UnitTests/GuardClauses.UnitTests.csproj

@@ -8,7 +8,7 @@
 
     <ItemGroup>
         <PackageReference Include="altcover" Version="8.6.68" />
-        <PackageReference Include="coverlet.msbuild" Version="3.2.0">
+        <PackageReference Include="coverlet.msbuild" Version="6.0.0">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>
         </PackageReference>