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

@@ -306,9 +306,9 @@
       "integrity": "sha1-8S4PPF13sLHN2RRpQuTpbB5N1SU="
     },
     "async": {
-      "version": "3.1.0",
-      "resolved": "https://registry.npmjs.org/async/-/async-3.1.0.tgz",
-      "integrity": "sha512-4vx/aaY6j/j3Lw3fbCHNWP0pPaTCew3F6F3hYyl/tHs/ndmV1q7NW9T5yuJ2XAGwdQrP+6Wu20x06U4APo/iQQ=="
+      "version": "3.2.4",
+      "resolved": "https://registry.npmjs.org/async/-/async-3.2.4.tgz",
+      "integrity": "sha512-iAB+JbDEGXhyIUavoDl9WP/Jj106Kz9DEn1DPgYw5ruDn0e3Wgi3sKFm55sASdGBNOQB8F59d9qQ7deqrHA8wQ=="
     },
     "async-chain-proxy": {
       "version": "0.1.6",
@@ -4237,9 +4237,9 @@
       },
       "dependencies": {
         "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"