Update dependency NUnit.Runners to v3

Author: renovate-bot

src/OpenInApp.Common.Tests/OpenInApp.Common.Tests.csproj

@@ -168,7 +168,7 @@
       <Version>3.6.1</Version>
     </PackageReference>
     <PackageReference Include="NUnit.Runners">
-      <Version>2.6.3</Version>
+      <Version>3.12.0</Version>
     </PackageReference>
     <PackageReference Include="OpenCover">
       <Version>4.6.519</Version>