Bump xunit from 2.6.2 to 2.6.3 (dotnet#1623)

Author: dependabot[bot]

.github/workflows/package.yml

@@ -93,6 +93,7 @@ jobs:
 
   sign:
     name: "Sign Package"
+    if: github.event_name != 'pull_request'
     needs: [pack]
     runs-on: windows-latest
     steps: 

Directory.Packages.props

@@ -28,7 +28,7 @@
     <PackageVersion Include="System.Security.Cryptography.Algorithms" Version="4.3.1" />
     <PackageVersion Include="System.Xml.ReaderWriter" Version="4.3.1" />
     <PackageVersion Include="System.ValueTuple" Version="4.5.0" />
-    <PackageVersion Include="xunit" Version="2.6.2" />
+    <PackageVersion Include="xunit" Version="2.6.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.4" />
   </ItemGroup>
 </Project>