Update xunit.runner.visualstudio to 3.1.0 (#244)

Author: dependabot[bot]

Notation.Plugin.AzureKeyVault.Tests/Notation.Plugin.AzureKeyVault.Tests.csproj

@@ -13,7 +13,7 @@
     <PackageReference Include="Moq.AutoMock" Version="3.5.0" />
     <PackageReference Include="System.Security.Cryptography.Pkcs" Version="9.0.4" />
     <PackageReference Include="xunit" Version="2.9.3" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="3.0.2">
+    <PackageReference Include="xunit.runner.visualstudio" Version="3.1.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>