Bump NUnit from 4.5.0 to 4.5.1

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

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

Author: dependabot[bot]

test/Diffs.Test.csproj

@@ -10,7 +10,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="NUnit" Version="4.5.0" />
+    <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>