Bump async from 2.6.3 to 3.2.4

Bumps [async](https://github.com/caolan/async) from 2.6.3 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/v2.6.3...v3.2.4)

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

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

package-lock.json

@@ -1435,7 +1435,7 @@
 		"node_modules/grunt-contrib-sass/node_modules/async": {
 			"version": "0.9.2",
 			"resolved": "https://registry.npmjs.org/async/-/async-0.9.2.tgz",
-			"integrity": "sha1-rqdNXmHB+JlhO/ZL2mbUx48v0X0=",
+			"integrity": "sha512-l6ToIJIotphWahxxHyzK9bnLR6kM4jJIIgLShZeqLY7iboHoGkdgFl7W2/Ivi4SkMJYGKqW8vSuk0uKUj6qsSw==",
 			"dev": true
 		},
 		"node_modules/grunt-contrib-uglify": {
@@ -1470,9 +1470,9 @@
 			}
 		},
 		"node_modules/grunt-contrib-watch/node_modules/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,
 			"dependencies": {
 				"lodash": "^4.17.14"
@@ -4606,7 +4606,7 @@
 		"node_modules/uglify-js/node_modules/async": {
 			"version": "0.2.10",
 			"resolved": "https://registry.npmjs.org/async/-/async-0.2.10.tgz",
-			"integrity": "sha1-trvgsGdLnXGXCMo43owjfLUmw9E=",
+			"integrity": "sha512-eAkdoKxU6/LkKDBzLpT+t6Ff5EtfSF4wx1WfJiPEEV7WNLnDaRXk0oVysiEPm262roaachGexwUv94WhSgN5TQ==",
 			"dev": true
 		},
 		"node_modules/uglify-to-browserify": {