Fix a few more compiler warnings

Signed-off-by: Ske <voltasalt@gmail.com>

Myriad/Cache/MemoryDiscordCache.cs

@@ -151,10 +151,11 @@ namespace Myriad.Cache
         public bool TryGetRole(ulong roleId, out Role role) =>
             _roles.TryGetValue(roleId, out role!);
 
-        public async IAsyncEnumerable<Guild> GetAllGuilds()
+        public IAsyncEnumerable<Guild> GetAllGuilds()
         {
-            foreach (var guild in _guilds.Values)
-                yield return guild.Guild;
+            return _guilds.Values
+                .Select(g => g.Guild)
+                .ToAsyncEnumerable();
         }
 
         public IEnumerable<Channel> GetGuildChannels(ulong guildId)

Myriad/Myriad.csproj

@@ -19,6 +19,7 @@
       <PackageReference Include="Polly" Version="7.2.1" />
       <PackageReference Include="Polly.Contrib.WaitAndRetry" Version="1.1.1" />
       <PackageReference Include="Serilog" Version="2.10.0" />
+      <PackageReference Include="System.Linq.Async" Version="5.0.0" />
     </ItemGroup>
 
 </Project>