Bump NUnit from 4.2.2 to 4.4.0 (#193)

---
updated-dependencies:
- dependency-name: NUnit
  dependency-version: 4.4.0
  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>

Author: dependabot[bot]

tests/UTF-unknown.Tests.csproj

@@ -11,7 +11,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
-    <PackageReference Include="NUnit" Version="4.2.2" />
+    <PackageReference Include="NUnit" Version="4.4.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="5.1.0" />
   </ItemGroup>