fix editable inputFormatters bug

com.unity.uiwidgets/Runtime/widgets/editable_text.cs

                 paste: true,
                 selectAll: true
             );
-            inputFormatters = inputFormatters ?? new List<TextInputFormatter>();
-            List<TextInputFormatter> formatters = new List<TextInputFormatter>();
-            if (inputFormatters == null) {
-                formatters = inputFormatters;
-            }
-            inputFormatters = maxLines == 1
-                ? new List<TextInputFormatter>() {
-                    BlacklistingTextInputFormatter.singleLineFormatter,
-                }
-                : inputFormatters;
+            this.inputFormatters = inputFormatters?? new List<TextInputFormatter>();
-                foreach (var formatter in formatters) {
-                    inputFormatters.Add(formatter);
-                }
+                this.inputFormatters.Add(BlacklistingTextInputFormatter.singleLineFormatter);
+            
             showCursor = showCursor ?? !readOnly;
 
             this.readOnly = readOnly;