Fix HDRP warning (#6396)

Author: adrien-de-tocqueville

com.unity.render-pipelines.high-definition/Runtime/Sky/VisualEnvironment.cs

@@ -180,7 +180,7 @@ public override int GetHashCode()
         /// <summary>Returns interpolated value from the visual environment.</summary>
         /// <param name="camera">The camera containing the volume stack to evaluate</param>
         /// <returns>The value for this parameter.</returns>
-        public float GetValue(HDCamera camera)
+        public virtual float GetValue(HDCamera camera)
         {
             if (value.mode == WindOverrideMode.Custom)
                 return value.customValue;
@@ -239,7 +239,7 @@ public override void Interp(WindParamaterValue from, WindParamaterValue to, floa
         /// <summary>Returns interpolated value from the visual environment.</summary>
         /// <param name="camera">The camera containing the volume stack to evaluate</param>
         /// <returns>The value for this parameter.</returns>
-        public float GetValue(HDCamera camera)
+        public override float GetValue(HDCamera camera)
         {
             // Multiply mode is not supported for wind orientation
             if (value.mode == WindOverrideMode.Multiply)