Bump NUnit3TestAdapter from 4.6.0 to 5.1.0 (#191)

---
updated-dependencies:
- dependency-name: NUnit3TestAdapter
  dependency-version: 5.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

tests/UTF-unknown.Tests.csproj

@@ -12,7 +12,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="NUnit" Version="3.14.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="5.1.0" />
   </ItemGroup>
 
   <ItemGroup>