chore(deps): [security] bump acorn from 5.7.3 to 5.7.4 (#425)

Bumps [acorn](https://github.com/acornjs/acorn) from 5.7.3 to 5.7.4. **This update includes a security fix.**
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@5.7.3...5.7.4)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

yarn.lock

@@ -1129,16 +1129,11 @@ acorn-walk@^6.0.1:
   integrity sha512-ugTb7Lq7u4GfWSqqpwE0bGyoBZNMTok/zDBXxfEG0QM50jNlGhIWjRC1pPN7bvV1anhF+bs+/gNcRw+o55Evbg==
 
 acorn@^5.5.3:
-  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"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.0.2.tgz#6a459041c320ab17592c6317abbfdf4bbaa98ca4"
-  integrity sha512-GXmKIvbrN3TV7aVqAzVFaMW8F8wzVX7voEBRO3bDA64+EX37YSayggRJP5Xig6HYHBkWKpFg9W5gg6orklubhg==
-
-acorn@^6.0.5:
+acorn@^6.0.1, acorn@^6.0.5:
   version "6.4.0"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.0.tgz#b659d2ffbafa24baf5db1cdbb2c94a983ecd2784"
   integrity sha512-gac8OEcQ2Li1dxIEWGZzsp2BitJxwkwcOm0zHAJLcPJaVvm58FRnk6RkuLRpU1EujipU2ZFODv2P9DLMfnV8mw==