Bump acorn from 6.4.0 to 6.4.1

Bumps [acorn](https://github.com/acornjs/acorn) from 6.4.0 to 6.4.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.4.0...6.4.1)

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

Author: dependabot[bot]

yarn.lock

@@ -29,9 +29,9 @@ acorn-jsx@^5.0.0:
   integrity sha512-tMUqwBWfLFbJbizRmEcWSLw6HnFzfdJs2sOJEOwwtVPMoH/0Ay+E703oZz78VSXZiiDcZrQ5XKjPIUQixhmgVw==
 
 acorn@^6.0.7:
-  version "6.4.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.0.tgz#b659d2ffbafa24baf5db1cdbb2c94a983ecd2784"
-  integrity sha512-gac8OEcQ2Li1dxIEWGZzsp2BitJxwkwcOm0zHAJLcPJaVvm58FRnk6RkuLRpU1EujipU2ZFODv2P9DLMfnV8mw==
+  version "6.4.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
+  integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
 ajv@^6.10.2, ajv@^6.9.1:
   version "6.10.2"