build(deps): [security] bump acorn from 6.1.0 to 6.4.1

Bumps [acorn](https://github.com/acornjs/acorn) from 6.1.0 to 6.4.1. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.1.0...6.4.1)

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

Author: dependabot-preview[bot]

yarn.lock

@@ -32,8 +32,8 @@ acorn-jsx@^5.1.0:
   resolved "https://registry.yarnpkg.com/acorn-jsx/-/acorn-jsx-5.1.0.tgz#294adb71b57398b0680015f0a38c563ee1db5384"
 
 acorn@^6.0.7:
-  version "6.1.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.1.0.tgz#b0a3be31752c97a0f7013c5f4903b71a05db6818"
+  version "6.4.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
 
 acorn@^7.1.0:
   version "7.1.0"