fix: use DiscordRichPresence 1.6.1.70 (compatible API, newer than 1.5.0.51)

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/a970ff72-5ae4-4b70-9bb2-0835b7799175

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

osu.Desktop/osu.Desktop.csproj

@@ -26,7 +26,7 @@
   <ItemGroup Label="Package References">
     <PackageReference Include="System.IO.Packaging" Version="10.0.7" />
     <!-- Held back due to invite bug in newer versions. See https://github.com/Lachee/discord-rpc-csharp/issues/286-->
-    <PackageReference Include="DiscordRichPresence" Version="1.143.0" />
+    <PackageReference Include="DiscordRichPresence" Version="1.6.1.70" />
     <PackageReference Include="Velopack" Version="0.0.1298" />
   </ItemGroup>
   <ItemGroup Label="Resources">