Change authentication to Forms if set to Basic

(cherry picked from commit dfb6fdfbeb7ce85b287b41fed80f2511727353e5)

src/NzbDrone.Core/Configuration/ConfigFileProvider.cs

@@ -210,9 +210,20 @@ namespace NzbDrone.Core.Configuration
                     return AuthenticationType.Forms;
                 }
 
-                return Enum.TryParse<AuthenticationType>(_authOptions.Method, out var enumValue)
+                var value = Enum.TryParse<AuthenticationType>(_authOptions.Method, out var enumValue)
                     ? enumValue
                     : GetValueEnum("AuthenticationMethod", AuthenticationType.None);
+
+#pragma warning disable CS0618 // Type or member is obsolete
+                if (value == AuthenticationType.Basic)
+#pragma warning restore CS0618 // Type or member is obsolete
+                {
+                    SetValue("AuthenticationMethod", AuthenticationType.Forms);
+
+                    return AuthenticationType.Forms;
+                }
+
+                return value;
             }
         }
 
@@ -386,6 +397,12 @@ namespace NzbDrone.Core.Configuration
             {
                 SetValue("EnableSsl", false);
             }
+#pragma warning disable CS0618 // Type or member is obsolete
+            if (AuthenticationMethod == AuthenticationType.Basic)
+#pragma warning restore CS0618 // Type or member is obsolete
+            {
+                SetValue("AuthenticationMethod", AuthenticationType.Forms);
+            }
         }
 
         private void DeleteOldValues()