:beetle: Fix key warning for children

Had a bug whit hot-reload, but gone when refreshing.

dev-front/src/mech/squad/Squad.tsx

@@ -57,7 +57,7 @@ function Squad({pickObservers} : {pickObservers: {[key: string] : MechObserver}}
             <h2>Custom squad</h2>
             <div className='mech-members'>
                 {squadMechs.map((m, index) => (
-                    <Member mech={m} remover={() => removeFromSquad(index)}/>
+                    <Member key={index} mech={m} remover={() => removeFromSquad(index)}/>
                 ))}
             </div>
             <div className='squad-description'>