Bump Microsoft.SourceLink.GitHub from 1.0.0 to 1.1.1 in /Rx.NET/Source

Bumps [Microsoft.SourceLink.GitHub](https://github.com/dotnet/sourcelink) from 1.0.0 to 1.1.1.
- [Release notes](https://github.com/dotnet/sourcelink/releases)
- [Commits](https://github.com/dotnet/sourcelink/compare/1.0.0...1.1.1)

---
updated-dependencies:
- dependency-name: Microsoft.SourceLink.GitHub
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Rx.NET/Source/Directory.build.props

@@ -27,7 +27,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All"/>
     <PackageReference Include="Nerdbank.GitVersioning" Version="3.4.244" PrivateAssets="all" />
   </ItemGroup>