Update dependency NUnit3TestAdapter to v6

Author: dependencyupdates[bot]

src/ApiTests/ApiTests.csproj

@@ -14,7 +14,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="NUnit" Version="3.14.0" />
     <PackageReference Include="NUnit.Analyzers" Version="4.6.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="6.0.0" />
     <PackageReference Include="Particular.Approvals" Version="1.1.1" />
     <PackageReference Include="PublicApiGenerator" Version="11.4.1" />
   </ItemGroup>

src/TestHarness/TestHarness.csproj

@@ -15,7 +15,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="NUnit" Version="3.14.0" />
     <PackageReference Include="NUnit.Analyzers" Version="4.6.0" />
-    <PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="6.0.0" />
   </ItemGroup>
 
 </Project>