chore: remove extraneous packageManager field (#6814)

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## Summary

Added by accident during monorepo migration.

## Test plan

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packages/react-native-reanimated/package.json

@@ -178,6 +178,5 @@
     "./lib/module/core.js",
     "./lib/module/initializers.js",
     "./lib/module/index.js"
-  ],
-  "packageManager": "[email protected]"
+  ]
 }