fix: upgrade css-vars-ponyfill from 2.4.3 to 2.4.7

Snyk has created this PR to upgrade css-vars-ponyfill from 2.4.3 to 2.4.7.

See this package in npm:
https://www.npmjs.com/package/css-vars-ponyfill

See this project in Snyk:
https://app.snyk.io/org/yext/project/0f7d62e5-8ca2-46bd-abb0-048a1a25e0fa?utm_source=github&utm_medium=referral&page=upgrade-pr

package.json

@@ -28,7 +28,7 @@
     "@yext/answers-storage": "^1.1.0",
     "@yext/rtf-converter": "^1.5.0",
     "cross-fetch": "^3.1.4",
-    "css-vars-ponyfill": "^2.4.3",
+    "css-vars-ponyfill": "^2.4.7",
     "gulp-sourcemaps": "^2.6.5",
     "handlebars": "^4.7.7",
     "js-levenshtein": "^1.1.6",