Merge pull request #315 from amplitude/AMP-70918-lerna6

AMP-70918 bump to lerna 6

Author: kelsonpw

package.json

@@ -20,7 +20,7 @@
     "flow-bin": "^0.100.0",
     "husky": "^1.3.1",
     "jest": "^24.8.0",
-    "lerna": "^4.0.0",
+    "lerna": "^6.5.1",
     "prettier": "^1.14.3",
     "pretty-quick": "^1.4.1"
   },