Bump NuGetizer from 1.0.5 to 1.2.1

Bumps [NuGetizer](https://github.com/devlooped/nugetizer) from 1.0.5 to 1.2.1.
- [Release notes](https://github.com/devlooped/nugetizer/releases)
- [Changelog](https://github.com/devlooped/nugetizer/blob/main/changelog.md)
- [Commits](devlooped/nugetizer@v1.0.5...v1.2.1)

---
updated-dependencies:
- dependency-name: NuGetizer
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

src/RxFree/RxFree.csproj

@@ -28,7 +28,7 @@ System.Reactive package for `IObservable<T>` producers.
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="NuGetizer" Version="1.0.5" />
+    <PackageReference Include="NuGetizer" Version="1.2.1" />
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="all" />
   </ItemGroup>