Bump microbundle from 0.11.0 to 0.12.0

Bumps [microbundle](https://github.com/developit/microbundle) from 0.11.0 to 0.12.0.
- [Release notes](https://github.com/developit/microbundle/releases)
- [Commits](https://github.com/developit/microbundle/compare/0.11.0...0.12.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -61,7 +61,7 @@
     "eslint-plugin-prettier": "^3.1.2",
     "husky": "^4.2.3",
     "lint-staged": "^10.1.1",
-    "microbundle": "^0.11.0",
+    "microbundle": "^0.12.0",
     "mocha": "^7.0.0",
     "prettier": "^2.0.2",
     "table": "^5.4.6",