Disable shadow copying so all tests pass in VS runner

Author: bording

LibGit2Sharp.Tests/LibGit2Sharp.Tests.csproj

@@ -23,10 +23,8 @@
   <ItemGroup>
     <Compile Include="..\LibGit2Sharp\Core\Platform.cs" Link="TestHelpers\Platform.cs" />
     <Compile Remove="desktop\**" Condition="'$(TargetFramework)' != 'net46'" />
-  </ItemGroup>
-
-  <ItemGroup>
     <Content Include="Resources\**\*.*" CopyToOutputDirectory="PreserveNewest" />
+    <None Update="xunit.runner.json" CopyToOutputDirectory="PreserveNewest" />
   </ItemGroup>
 
   <Target Name="CopyTestAppExes" AfterTargets="ResolveProjectReferences">

LibGit2Sharp.Tests/xunit.runner.json

@@ -0,0 +1,4 @@
+{
+    "$schema": "https://xunit.github.io/schema/current/xunit.runner.schema.json",
+    "shadowCopy":  false
+}