Use GetHashCode when combining int values

src/ImageSharp/MetaData/Profiles/ICC/Curves/IccParametricCurve.cs

@@ -156,7 +156,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
         {
             unchecked
             {
-                int hashCode = (int)this.Type;
+                int hashCode = this.Type.GetHashCode();
                 hashCode = HashHelpers.Combine(hashCode, this.G.GetHashCode());
                 hashCode = HashHelpers.Combine(hashCode, this.A.GetHashCode());
                 hashCode = HashHelpers.Combine(hashCode, this.B.GetHashCode());

src/ImageSharp/MetaData/Profiles/ICC/Curves/IccResponseCurve.cs

@@ -74,7 +74,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
         public override int GetHashCode()
         {
             return HashHelpers.Combine(
-                (int)this.CurveType,
+                this.CurveType.GetHashCode(),
                 this.XyzValues.GetHashCode(),
                 this.ResponseArrays.GetHashCode());
         }

src/ImageSharp/MetaData/Profiles/ICC/TagDataEntries/IccChromaticityTagDataEntry.cs

@@ -112,7 +112,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
         {
             return HashHelpers.Combine(
                 base.GetHashCode(),
-                (int)this.ColorantType,
+                this.ColorantType.GetHashCode(),
                 this.ChannelValues.GetHashCode());
         }
 

src/ImageSharp/MetaData/Profiles/ICC/TagDataEntries/IccViewingConditionsTagDataEntry.cs

@@ -90,7 +90,7 @@ namespace SixLabors.ImageSharp.MetaData.Profiles.Icc
                 base.GetHashCode(),
                 this.IlluminantXyz.GetHashCode(),
                 this.SurroundXyz.GetHashCode(),
-                (int)this.Illuminant);
+                this.Illuminant.GetHashCode());
         }
     }
 }