Merge pull request #1226 from dotnet/dependabot/nuget/Rx.NET/Source/DiffPlex-1.6.3

Author: dependabot-preview[bot]

Rx.NET/Source/tests/Tests.System.Reactive.ApiApprovals/Tests.System.Reactive.ApiApprovals.csproj

@@ -29,7 +29,7 @@
     <PackageReference Include="Verify.Xunit" Version="1.34.2" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
-    <PackageReference Include="DiffPlex" Version="1.6.2" />
+    <PackageReference Include="DiffPlex" Version="1.6.3" />
     <PackageReference Include="PublicApiGenerator" Version="10.1.0" />
   </ItemGroup>