Add unique keys to modifier controls

- Added a unique `key` prop to `FormControlLabel` in `Modifiers.js` to improve React rendering performance and prevent key warning errors.

src/renderer/screens/Editor/Sidebar/Modifiers.js

@@ -55,6 +55,7 @@ const Modifiers = (props) => {
     const modifier = modifiers[mod];
     return (
       <FormControlLabel
+        key={modifier.code}
         control={
           <Switch
             size="small"