Remove unnecessary keys

Author: eps1lon

packages/material-ui/src/Rating/Rating.js

@@ -250,14 +250,14 @@ function RatingItem(props) {
 
   if (readOnly) {
     return (
-      <span key={itemValue} {...labelProps}>
+      <span {...labelProps}>
         {container}
       </span>
     );
   }
 
   return (
-    <React.Fragment key={itemValue}>
+    <React.Fragment>
       <RatingLabel
         styleProps={{ ...styleProps, emptyValueFocused: undefined }}
         htmlFor={id}