build(deps): bump Xamarin.AndroidX.AppCompat in /src (#2949)

Bumps [Xamarin.AndroidX.AppCompat](https://github.com/xamarin/AndroidX) from 1.3.1.1 to 1.3.1.3.
- [Release notes](https://github.com/xamarin/AndroidX/releases)
- [Commits](https://github.com/xamarin/AndroidX/commits)

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

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

src/ReactiveUI.AndroidX/ReactiveUI.AndroidX.csproj

@@ -11,7 +11,7 @@
 
   <ItemGroup>
     <PackageReference Include="System.Runtime.Serialization.Primitives" Version="4.3.0" />
-    <PackageReference Include="Xamarin.AndroidX.AppCompat" Version="1.3.1.1" />
+    <PackageReference Include="Xamarin.AndroidX.AppCompat" Version="1.3.1.3" />
     <PackageReference Include="Xamarin.AndroidX.Fragment" Version="1.3.6.3" />
     <PackageReference Include="Xamarin.AndroidX.Preference" Version="1.1.1.9" />
     <PackageReference Include="Xamarin.AndroidX.RecyclerView" Version="1.2.1.3" />