Bump acorn from 5.7.3 to 5.7.4 (#19)

Bumps [acorn](https://github.com/acornjs/acorn) from 5.7.3 to 5.7.4.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/5.7.3...5.7.4)

---
updated-dependencies:
- dependency-name: acorn
  dependency-type: indirect
...
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

yarn.lock

@@ -248,9 +248,9 @@ acorn-walk@^6.0.1:
   integrity sha512-ugTb7Lq7u4GfWSqqpwE0bGyoBZNMTok/zDBXxfEG0QM50jNlGhIWjRC1pPN7bvV1anhF+bs+/gNcRw+o55Evbg==
 
 acorn@^5.0.0, acorn@^5.5.3, acorn@^5.6.2:
-  version "5.7.3"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.7.3.tgz#67aa231bf8812974b85235a96771eb6bd07ea279"
-  integrity sha512-T/zvzYRfbVojPWahDsE5evJdHb3oJoQfFbsrKM7w5Zcs++Tr257tia3BmMP8XYVjp1S9RZXQMh7gao96BlqZOw==
+  version "5.7.4"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.7.4.tgz#3e8d8a9947d0599a1796d10225d7432f4a4acf5e"
+  integrity sha512-1D++VG7BhrtvQpNbBzovKNc1FLGGEE/oGe7b9xJm/RFHMBeUaUGpluV9RLjZa47YFdPcDAenEYuq9pQPcMdLJg==
 
 acorn@^6.0.1:
   version "6.0.2"