Add missing repository information

Author: kzu

src/PackageReferenceCleaner/PackageReferenceCleaner.csproj

@@ -17,6 +17,10 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
     <PackageReference Include="NuGetizer" Version="1.0.1" Pack="false" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.0.1" Pack="false" />
     <PackageReference Include="Devlooped.SponsorLink" Version="0.10.2" />