Remove es5-ext pin

[cnlucas]

Summary

What we're after:
es5-ext is being pulled in through es6-weak-map. We should regularly check if es6-weak-map has updated their versioning so we can remove this pin.

Related issues

#6132

Completion criteria

es5-ext pin is removed and we are still not receiving any snyk notifications about vulnerabilities

Future work

Other future work that may be needed following this issue's completion.