Update dependency es6-promise to v4.2.6

Author: renovate-bot

package.json

@@ -36,7 +36,7 @@
   },
   "dependencies": {
     "@turf/helpers": "6.1.4",
-    "es6-promise": "4.2.5",
+    "es6-promise": "4.2.6",
     "mapbox-gl": "0.49.0",
     "unfetch": "3.1.1"
   },

yarn.lock

@@ -2743,9 +2743,9 @@ es6-iterator@~2.0.3:
     es5-ext "^0.10.35"
     es6-symbol "^3.1.1"
 
-es6-promise@4.2.5:
-  version "4.2.5"
-  resolved "https://registry.yarnpkg.com/es6-promise/-/es6-promise-4.2.5.tgz#da6d0d5692efb461e082c14817fe2427d8f5d054"
+es6-promise@4.2.6:
+  version "4.2.6"
+  resolved "https://registry.yarnpkg.com/es6-promise/-/es6-promise-4.2.6.tgz#b685edd8258886365ea62b57d30de28fadcd974f"
 
 es6-promise@^4.0.3:
   version "4.2.4"