NuGet(deps): Bump Discord.Net in /Izzy-MoonbotTests

Bumps [Discord.Net](https://github.com/discord-net/Discord.Net) from 3.12.0 to 3.13.0.
- [Release notes](https://github.com/discord-net/Discord.Net/releases)
- [Changelog](https://github.com/discord-net/Discord.Net/blob/dev/CHANGELOG.md)
- [Commits](discord-net/Discord.Net@3.12.0...3.13.0)

---
updated-dependencies:
- dependency-name: Discord.Net
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Izzy-Moonbot/Izzy-Moonbot.csproj

@@ -27,7 +27,7 @@
     </ItemGroup>
 
     <ItemGroup>
-        <PackageReference Include="Discord.Net" Version="3.12.0" />
+        <PackageReference Include="Discord.Net" Version="3.13.0" />
         <PackageReference Include="Flurl.Http" Version="3.2.4" />
         <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.19.5" />
         <PackageReference Include="Microsoft.Extensions.Hosting" Version="7.0.1" />