misc: chore: Use explicit types in Vulkan project

src/Ryujinx.Graphics.Vulkan/BackgroundResources.cs

@@ -110,7 +110,7 @@ namespace Ryujinx.Graphics.Vulkan
         {
             lock (_resources)
             {
-                foreach (var resource in _resources.Values)
+                foreach (BackgroundResource resource in _resources.Values)
                 {
                     resource.Dispose();
                 }