Update optional-chaining for new version (v7.6.0)

Author: renatoagds

packages/babel-preset-react-app/package.json

@@ -26,7 +26,7 @@
     "@babel/plugin-proposal-decorators": "7.6.0",
     "@babel/plugin-proposal-nullish-coalescing-operator": "7.4.4",
     "@babel/plugin-proposal-object-rest-spread": "7.5.5",
-    "@babel/plugin-proposal-optional-chaining": "7.2.0",
+    "@babel/plugin-proposal-optional-chaining": "7.6.0",
     "@babel/plugin-syntax-dynamic-import": "7.2.0",
     "@babel/plugin-transform-destructuring": "7.6.0",
     "@babel/plugin-transform-flow-strip-types": "7.4.4",