chore(deps): bump acorn from 6.0.4 to 6.4.1

Bumps [acorn](https://github.com/acornjs/acorn) from 6.0.4 to 6.4.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.0.4...6.4.1)

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

yarn.lock

@@ -1215,20 +1215,10 @@ acorn-walk@^6.0.1:
   resolved "https://registry.yarnpkg.com/acorn-walk/-/acorn-walk-6.1.1.tgz#d363b66f5fac5f018ff9c3a1e7b6f8e310cc3913"
   integrity sha512-OtUw6JUTgxA2QoqqmrmQ7F2NYqiBPi/L2jqHyFtllhOUvXYQXf0Z1CYUinIfyT4bTCGmrA7gX9FvHA81uzCoVw==
 
-acorn@^6.0.1:
-  version "6.0.4"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.0.4.tgz#77377e7353b72ec5104550aa2d2097a2fd40b754"
-  integrity sha512-VY4i5EKSKkofY2I+6QLTbTTN/UvEQPCo6eiwzzSaSWfpaDhOmStMCMod6wmuPciNq+XS0faCglFu2lHZpdHUtg==
-
-acorn@^6.0.4, acorn@^6.0.7:
-  version "6.1.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.1.0.tgz#b0a3be31752c97a0f7013c5f4903b71a05db6818"
-  integrity sha512-MW/FjM+IvU9CgBzjO3UIPCE2pyEwUsoFl+VGdczOPEdxfGFjuKny/gN54mOuX7Qxmb9Rg9MCn2oKiSUeW+pjrw==
-
-acorn@^6.2.1:
-  version "6.2.1"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.2.1.tgz#3ed8422d6dec09e6121cc7a843ca86a330a86b51"
-  integrity sha512-JD0xT5FCRDNyjDda3Lrg/IxFscp9q4tiYtxE1/nOzlKCk7hIRuYjhq1kCNkbPjMRMZuFq20HNQn1I9k8Oj0E+Q==
+acorn@^6.0.1, acorn@^6.0.4, acorn@^6.0.7, acorn@^6.2.1:
+  version "6.4.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
+  integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
 after@0.8.2:
   version "0.8.2"