build(deps): bump System.Reactive from 4.4.1 to 5.0.0 (#269)

Bumps [System.Reactive](https://github.com/dotnet/reactive) from 4.4.1 to 5.0.0.
- [Release notes](https://github.com/dotnet/reactive/releases)
- [Commits](dotnet/reactive@rxnet-v4.4.1...ixnet-v5.0.0)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Sample/SextantSample.Android/SextantSample.Android.csproj

@@ -66,7 +66,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="System.Reactive" Version="4.4.*" />
+    <PackageReference Include="System.Reactive" Version="5.0.*" />
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
     <PackageReference Include="Xamarin.Android.Support.Design" Version="28.0.0.3" />
     <PackageReference Include="Xamarin.Android.Support.v7.AppCompat" Version="28.0.0.3" />

src/Sextant.iOS.Runner/Sextant.iOS.Runner.csproj

@@ -132,7 +132,7 @@
       <Version>4.4.1</Version>
     </PackageReference>
     <PackageReference Include="System.Reactive">
-      <Version>4.4.1</Version>
+      <Version>5.0.0</Version>
     </PackageReference>
     <PackageReference Include="xunit">
       <Version>2.4.1</Version>