chore: update dependency microbundle to ^0.15.0

Author: renovate-bot

package.json

@@ -42,7 +42,7 @@
     "esm": "^3.2.25",
     "husky": "^4.0.0",
     "lint-staged": "^10.0.0",
-    "microbundle": "^0.13.0",
+    "microbundle": "^0.15.0",
     "prettier": "^1.13.4",
     "standard-version": "^9.0.0"
   },