build(deps): bump async from 3.2.3 to 3.2.4 in /src

Bumps [async](https://github.com/caolan/async) from 3.2.3 to 3.2.4.
- [Release notes](https://github.com/caolan/async/releases)
- [Changelog](https://github.com/caolan/async/blob/master/CHANGELOG.md)
- [Commits](https://github.com/caolan/async/compare/v3.2.3...v3.2.4)

---
updated-dependencies:
- dependency-name: async
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

src/package-lock.json

@@ -1227,9 +1227,9 @@
       "integrity": "sha1-8S4PPF13sLHN2RRpQuTpbB5N1SU="
     },
     "async": {
-      "version": "3.2.3",
-      "resolved": "https://registry.npmjs.org/async/-/async-3.2.3.tgz",
-      "integrity": "sha512-spZRyzKL5l5BZQrr/6m/SqFdBN0q3OCI0f9rjfBzCMBIP4p75P620rR3gTmaksNOhmzgdxcaxdNfMy6anrbM0g=="
+      "version": "3.2.4",
+      "resolved": "https://registry.npmjs.org/async/-/async-3.2.4.tgz",
+      "integrity": "sha512-iAB+JbDEGXhyIUavoDl9WP/Jj106Kz9DEn1DPgYw5ruDn0e3Wgi3sKFm55sASdGBNOQB8F59d9qQ7deqrHA8wQ=="
     },
     "asynckit": {
       "version": "0.4.0",

src/package.json

@@ -30,7 +30,7 @@
     }
   ],
   "dependencies": {
-    "async": "^3.2.2",
+    "async": "^3.2.4",
     "clean-css": "^5.3.2",
     "cookie-parser": "^1.4.6",
     "cross-spawn": "^7.0.3",