HDRP: Decal - Silent a warning

com.unity.render-pipelines.high-definition/HDRP/Editor/Upgraders/UpgradeMenuItem.cs

             // When _HdrpVersion don't exist we MUST create it, otherwise next call to
             // mat.SetFloat("_HdrpVersion", value) will just put the default value instead of the value we pass!
             // a call to GetFloat("_HdrpVersion") solve this.
-            float useless = mat.GetFloat("_HdrpVersion");
+#pragma warning disable 219 // Silent warning
+            float unused = mat.GetFloat("_HdrpVersion");
+#pragma warning restore 219
 
             return 0.0f;
         }