build(deps): bump Xamarin.AndroidX.Fragment in /samples (#278)

Bumps [Xamarin.AndroidX.Fragment](https://github.com/xamarin/AndroidX) from 1.3.3 to 1.3.4.
- [Release notes](https://github.com/xamarin/AndroidX/releases)
- [Commits](https://github.com/xamarin/AndroidX/commits)

---
updated-dependencies:
- dependency-name: Xamarin.AndroidX.Fragment
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

samples/LoginApp.Android/LoginApp.Android.csproj

@@ -79,7 +79,7 @@
     <!-- We are pinning transitive deps versions coming from ReactiveUI.AndroidX.
          See: https://github.com/reactiveui/ReactiveUI.Validation/pull/216#issuecomment-783218308 -->
     <PackageReference Include="Xamarin.AndroidX.Preference" Version="1.1.1.8" />
-    <PackageReference Include="Xamarin.AndroidX.Fragment" Version="1.3.3" />
+    <PackageReference Include="Xamarin.AndroidX.Fragment" Version="1.3.4" />
     <PackageReference Include="Xamarin.AndroidX.RecyclerView" Version="1.2.0" />
   </ItemGroup>
   <ItemGroup>