Bump Discord.Net from 3.15.0 to 3.15.2

Bumps [Discord.Net](https://github.com/discord-net/Discord.Net) from 3.15.0 to 3.15.2.
- [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@3.15.0...3.15.2)

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

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

GrammarNazi.App/GrammarNazi.App.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Discord.Net" Version="3.15.0" />
+    <PackageReference Include="Discord.Net" Version="3.15.2" />
     <PackageReference Include="FirebaseAuthentication.net" Version="4.1.0" />
     <PackageReference Include="FirebaseDatabase.net" Version="4.2.0" />
     <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.20.1" />

GrammarNazi.Core/GrammarNazi.Core.csproj

@@ -5,7 +5,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Discord.Net" Version="3.15.0" />
+    <PackageReference Include="Discord.Net" Version="3.15.2" />
     <PackageReference Include="FirebaseDatabase.net" Version="4.2.0" />
     <PackageReference Include="Markdig" Version="0.37.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="8.0.6" />

GrammarNazi.Domain/GrammarNazi.Domain.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Discord.Net" Version="3.15.0" />
+    <PackageReference Include="Discord.Net" Version="3.15.2" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="Telegram.Bot" Version="19.0.0" />
   </ItemGroup>