Bump OxyPlot.Wpf from 2.0.0 to 2.2.0

Bumps [OxyPlot.Wpf](https://github.com/oxyplot/oxyplot) from 2.0.0 to 2.2.0.
- [Release notes](https://github.com/oxyplot/oxyplot/releases)
- [Changelog](https://github.com/oxyplot/oxyplot/blob/develop/CHANGELOG.md)
- [Commits](oxyplot/oxyplot@v2.0.0...v2.2.0)

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

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

Author: dependabot[bot]

Shadowsocks.WPF/Shadowsocks.WPF.csproj

@@ -51,7 +51,7 @@
   <ItemGroup>
     <PackageReference Include="MaterialDesignThemes" Version="4.9.0" />
     <PackageReference Include="MdXaml" Version="1.21.0" />
-    <PackageReference Include="OxyPlot.Wpf" Version="2.1.2" />
+    <PackageReference Include="OxyPlot.Wpf" Version="2.2.0" />
     <PackageReference Include="ReactiveUI.Events.WPF" Version="15.1.1" />
     <PackageReference Include="ReactiveUI.Fody" Version="19.4.1" />
     <PackageReference Include="ReactiveUI.Validation" Version="3.1.7" />