Bump async from 2.6.3 to 2.6.4

Bumps [async](https://github.com/caolan/async) from 2.6.3 to 2.6.4.
- [Release notes](https://github.com/caolan/async/releases)
- [Changelog](https://github.com/caolan/async/blob/v2.6.4/CHANGELOG.md)
- [Commits](https://github.com/caolan/async/compare/v2.6.3...v2.6.4)

---
updated-dependencies:
- dependency-name: async
  dependency-type: indirect
...

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

package.json

@@ -37,7 +37,7 @@
     "zone.js": "~0.8.26"
   },
   "devDependencies": {
-    "@angular-devkit/build-angular": "^15.0.0",
+    "@angular-devkit/build-angular": "^0.13.10",
     "@angular/cli": "~6.2.5",
     "@angular/compiler-cli": "^6.1.0",
     "@angular/language-service": "^6.1.0",