Bump NUnit from 4.4.0 to 4.5.1

---
updated-dependencies:
- dependency-name: NUnit
  dependency-version: 4.5.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

UnitTests/UnitTests.csproj

@@ -26,7 +26,7 @@
     <PackageReference Include="AltCover" Version="9.0.102" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.4" />
-    <PackageReference Include="nunit" Version="4.4.0" />
+    <PackageReference Include="nunit" Version="4.5.1" />
     <PackageReference Include="NUnit.Analyzers" Version="4.11.2">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>