Downgrade core-js to fix esm.sh build issue (#1207)

package.json

@@ -52,7 +52,7 @@
     "babel-loader": "9.1.2",
     "codecov": "^3.8.3",
     "concurrently": "7.4.0",
-    "core-js": "3.30.2",
+    "core-js": "3.27.1",
     "cpx2": "4.2.3",
     "eslint": "^7.32.0",
     "eslint-plugin-no-jquery": "^2.7.0",
@@ -121,7 +121,7 @@
     "DOCS:update:test-deps": "If CI succeeds, these should be good to update",
     "update:test-deps": "npm i @babel/eslint-parser@latest @open-wc/testing-helpers@latest @types/jest@latest codecov@latest eslint@7 eslint-plugin-testcafe@latest jest@latest sinon@latest testcafe@latest",
     "DOCS:update:build-deps": "These can cause strange changes, so do an npm run build + check file size (git diff --stat), and check the site is as expected",
-    "update:build-deps": "npm i @babel/core@latest @babel/preset-env@latest @babel/plugin-proposal-class-properties@latest @babel/plugin-proposal-decorators@latest babel-loader@latest core-js@latest regenerator-runtime@latest sass@latest svgo@latest webpack@latest webpack-cli@latest",
+    "update:build-deps": "npm i @babel/core@latest @babel/preset-env@latest @babel/plugin-proposal-class-properties@latest @babel/plugin-proposal-decorators@latest babel-loader@latest core-js@3.27.1 regenerator-runtime@latest sass@latest svgo@latest webpack@latest webpack-cli@latest",
     "codecov": "npx codecov"
   }
 }