build: bump @webcomponents/custom-elements from 1.4.2 to 1.4.3

Bumps [@webcomponents/custom-elements](https://github.com/webcomponents/polyfills/tree/HEAD/packages/custom-elements) from 1.4.2 to 1.4.3.
- [Release notes](https://github.com/webcomponents/polyfills/releases)
- [Changelog](https://github.com/webcomponents/polyfills/blob/master/packages/custom-elements/CHANGELOG.md)
- [Commits](https://github.com/webcomponents/polyfills/commits/@webcomponents/custom-elements@1.4.3/packages/custom-elements)

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

yarn.lock

@@ -2227,9 +2227,9 @@
     eslint-visitor-keys "^2.0.0"
 
 "@webcomponents/custom-elements@^1.1.0":
-  version "1.4.2"
-  resolved "https://registry.yarnpkg.com/@webcomponents/custom-elements/-/custom-elements-1.4.2.tgz#a6fe80325c2b09e88e988c712144bc667c565499"
-  integrity sha512-bLw2XH9+2NBwmn7BI6WA2oIo2eOfBpl+GjAqkF/qnkZ8kq3HY5tKYTxtKowWALAferTp3wKD8W6FSn5OyK+rtQ==
+  version "1.4.3"
+  resolved "https://registry.yarnpkg.com/@webcomponents/custom-elements/-/custom-elements-1.4.3.tgz#1800d49f38bb4425ebfd160b50115e62776109d7"
+  integrity sha512-iD0YW46SreUQANGccywK/eC+gZELNHocZZrY2fGwrIlx/biQOTkAF9IohisibHbrmIHmA9pVCIdGwzfO+W0gig==
 
 JSONStream@^1.0.4, JSONStream@^1.2.1:
   version "1.3.5"