Bump NUnit from 4.3.2 to 4.4.0

---
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] <support@github.com>

Author: dependabot[bot]

UnitTests/UnitTests.csproj

@@ -14,7 +14,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
-    <PackageReference Include="NUnit" Version="4.3.2" />
+    <PackageReference Include="NUnit" Version="4.4.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
     <PackageReference Include="NUnit.Analyzers" Version="4.6.0">
       <PrivateAssets>all</PrivateAssets>