build(deps): 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.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.0.2...6.4.1)

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

Author: dependabot[bot]

yarn.lock

@@ -1131,15 +1131,10 @@ acorn-walk@^6.0.1:
   resolved "https://registry.yarnpkg.com/acorn-walk/-/acorn-walk-6.1.0.tgz#c957f4a1460da46af4a0388ce28b4c99355b0cbc"
   integrity sha512-ugTb7Lq7u4GfWSqqpwE0bGyoBZNMTok/zDBXxfEG0QM50jNlGhIWjRC1pPN7bvV1anhF+bs+/gNcRw+o55Evbg==
 
-acorn@^6.0.1, acorn@^6.0.2:
-  version "6.0.2"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.0.2.tgz#6a459041c320ab17592c6317abbfdf4bbaa98ca4"
-  integrity sha512-GXmKIvbrN3TV7aVqAzVFaMW8F8wzVX7voEBRO3bDA64+EX37YSayggRJP5Xig6HYHBkWKpFg9W5gg6orklubhg==
-
-acorn@^6.2.1:
-  version "6.3.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.3.0.tgz#0087509119ffa4fc0a0041d1e93a417e68cb856e"
-  integrity sha512-/czfa8BwS88b9gWQVhc8eknunSA2DoJpJyTQkhheIf5E48u1N0R4q/YxxsAeqRrmK9TQ/uYfgLDfZo91UlANIA==
+acorn@^6.0.1, acorn@^6.0.2, acorn@^6.2.1:
+  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"