Update image URLs in TestUtils to use 'main' branch

Author: IvanMurzak

Assets/_PackageRoot/Tests/Base/Utils/TestUtils.cs

@@ -12,9 +12,9 @@ public static partial class TestUtils
     {
         public static readonly string[] ImageURLs =
         {
-            "https://github.com/IvanMurzak/Unity-ImageLoader/raw/master/Test%20Images/ImageA.jpg",
-            "https://github.com/IvanMurzak/Unity-ImageLoader/raw/master/Test%20Images/ImageB.png",
-            "https://github.com/IvanMurzak/Unity-ImageLoader/raw/master/Test%20Images/ImageC.png"
+            "https://github.com/IvanMurzak/Unity-ImageLoader/raw/main/Test%20Images/ImageA.jpg",
+            "https://github.com/IvanMurzak/Unity-ImageLoader/raw/main/Test%20Images/ImageB.png",
+            "https://github.com/IvanMurzak/Unity-ImageLoader/raw/main/Test%20Images/ImageC.png"
         };
         public static string IncorrectImageURL => $"https://doesntexist.com/{Guid.NewGuid()}.png";
         public static IEnumerable<string> IncorrectImageURLs(int count = 3) => Enumerable.Range(0, count).Select(_ => IncorrectImageURL);