fix: broken build, refs NOISSUE

song_of_the_day/SongValidators/Base64UrlImageBuilder.cs

@@ -9,11 +9,17 @@ public class Base64UrlImageBuilder
             var httpClient = new HttpClient();
             var response = (httpClient.GetAsync(new Uri($"{value}"))).Result;
             var bytes = (response.Content.ReadAsByteArrayAsync()).Result;
-            FileContents = Convert.ToBase64String(bytes);
+            _fileContents = Convert.ToBase64String(bytes);
         }
     }
 
-    private required string FileContents { get; set; }
+    private string _fileContents = string.Empty;
+
+    public string FileContents { 
+        get {
+            return _fileContents;
+        }
+    } 
 
     public override string ToString()
     {