Update Microsoft.CodeAnalysis

Currently conflicts with anything depending on `Microsoft.CodeAnalysis` > 3.3

src/Discord.Net.Analyzers/Discord.Net.Analyzers.csproj

@@ -7,7 +7,7 @@
     <TargetFrameworks>netstandard2.0;netstandard2.1</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis" Version="3.3.1" />
+    <PackageReference Include="Microsoft.CodeAnalysis" Version="3.9.0" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Discord.Net.Commands\Discord.Net.Commands.csproj" />