Bump NUnit from 3.13.3 to 4.5.1

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

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

Author: dependabot[bot]

Source/LittleScriptBuddy/LittleScriptBuddy.Domain.Tests/LittleScriptBuddy.Domain.Tests.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.4.0" />
-    <PackageReference Include="NUnit" Version="3.13.3" />
+    <PackageReference Include="NUnit" Version="4.5.1" />
     <PackageReference Include="NUnit3TestAdapter" Version="6.2.0" />
   </ItemGroup>