Update dependency NUnit to 4.5.1

Author: renovate[bot]

src/Cody.Core.Tests/Cody.Core.Tests.csproj

@@ -61,7 +61,7 @@
       <Version>4.18.4</Version>
     </PackageReference>
     <PackageReference Include="NUnit">
-      <Version>4.2.2</Version>
+      <Version>4.5.1</Version>
     </PackageReference>
     <PackageReference Include="NUnit3TestAdapter">
       <Version>4.6.0</Version>