chore: update metro and merge deps (#124)

### Summary

We have a security alert around `merge` so I bumped that, also upgraded to latest metro preset version (it's still Node 8 compatible), updated RN to 0.58.6

Removed the version check for Flow as we always use local version anyway.

### Test plan

Check build directory

.flowconfig

@@ -75,6 +75,3 @@ include_warnings=true
 .*/Libraries/StyleSheet/StyleSheetValidation.js
 .*/Libraries/Text/TextAncestor.js
 .*/Libraries/YellowBox/UI/YellowBoxList.js
-
-[version]
-^0.93.0

package.json

@@ -23,9 +23,9 @@
     "flow-bin": "^0.94.0",
     "flow-copy-source": "^2.0.2",
     "jest": "^24.1.0",
-    "metro-react-native-babel-preset": "^0.49.1",
+    "metro-react-native-babel-preset": "^0.52.0",
     "react": "^16.8.3",
-    "react-native": "^0.58.3",
+    "react-native": "^0.58.6",
     "react-test-renderer": "^16.8.3",
     "release-it": "^10.0.0",
     "strip-ansi": "^5.0.0",
@@ -40,13 +40,13 @@
   },
   "scripts": {
     "test": "jest",
-    "flow-check": "flow check --ignore-version",
+    "flow-check": "flow check",
     "typescript-check": "tsc --noEmit --skipLibCheck --jsx react ./typings/__tests__/*",
     "lint": "eslint src --cache",
     "release": "release-it",
     "prepublish": "yarn build && yarn copy-flowtypes",
     "copy-flowtypes": "flow-copy-source --ignore __tests__/*.js src build",
-    "build": "rm -rf build; babel src --out-dir build --presets=module:metro-react-native-babel-preset  --ignore 'src/__tests__/*'"
+    "build": "rm -rf build; babel src --out-dir build --ignore 'src/__tests__/*'"
   },
   "jest": {
     "preset": "react-native",