[Security] Bump acorn from 6.0.2 to 6.4.1

Bumps [acorn](https://github.com/acornjs/acorn) from 6.0.2 to 6.4.1. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.0.2...6.4.1)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

yarn.lock

@@ -565,9 +565,9 @@ acorn-walk@^6.0.1:
   integrity sha512-ugTb7Lq7u4GfWSqqpwE0bGyoBZNMTok/zDBXxfEG0QM50jNlGhIWjRC1pPN7bvV1anhF+bs+/gNcRw+o55Evbg==
 
 acorn@^6.0.1:
-  version "6.0.2"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.0.2.tgz#6a459041c320ab17592c6317abbfdf4bbaa98ca4"
-  integrity sha512-GXmKIvbrN3TV7aVqAzVFaMW8F8wzVX7voEBRO3bDA64+EX37YSayggRJP5Xig6HYHBkWKpFg9W5gg6orklubhg==
+  version "6.4.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
+  integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
 acorn@^7.1.0:
   version "7.1.0"