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-lock.json

@@ -2169,9 +2169,9 @@
             "dev": true
         },
         "async": {
-            "version": "2.6.3",
-            "resolved": "https://registry.npmjs.org/async/-/async-2.6.3.tgz",
-            "integrity": "sha512-zflvls11DCy+dQWzTW2dzuilv8Z5X/pjfmZOWba6TNIVDm+2UDaJmXSOXlasHKfNBs8oo3M0aT50fDEWfKZjXg==",
+            "version": "2.6.4",
+            "resolved": "https://registry.npmjs.org/async/-/async-2.6.4.tgz",
+            "integrity": "sha512-mzo5dfJYwAn29PeiJ0zvwTo04zj8HDJj0Mn8TD7sno7q12prdbnasKJHhkm2c1LgrhlJ0teaea8860oxi51mGA==",
             "dev": true,
             "requires": {
                 "lodash": "^4.17.14"