Bump acorn from 5.5.3 to 5.7.4

Bumps [acorn](https://github.com/acornjs/acorn) from 5.5.3 to 5.7.4.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@5.5.3...5.7.4)

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

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

Author: dependabot[bot]

yarn.lock

@@ -1206,8 +1206,9 @@ acorn-globals@^4.1.0:
     acorn "^5.0.0"
 
 acorn@^5.0.0, acorn@^5.3.0:
-  version "5.5.3"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.5.3.tgz#f473dd47e0277a08e28e9bec5aeeb04751f0b8c9"
+  version "5.7.4"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.7.4.tgz#3e8d8a9947d0599a1796d10225d7432f4a4acf5e"
+  integrity sha512-1D++VG7BhrtvQpNbBzovKNc1FLGGEE/oGe7b9xJm/RFHMBeUaUGpluV9RLjZa47YFdPcDAenEYuq9pQPcMdLJg==
 
 aggregate-error@^3.0.0:
   version "3.0.0"