Bump WS4N to latest stable

src/Discord.Net.Providers.WS4Net/Discord.Net.Providers.WS4Net.csproj

@@ -10,6 +10,6 @@
     <ProjectReference Include="..\Discord.Net.Core\Discord.Net.Core.csproj" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="WebSocket4Net" Version="0.15.0" />
+    <PackageReference Include="WebSocket4Net" Version="0.15.2" />
   </ItemGroup>
 </Project>