Rev dependencies, ESM, and fix unit test harness

[joshperry]

updates all deps to latest
adopts native ESM (since node 14)
replace proxyquire with esmock
updates code for newest got lib
update eslint config to es2020+ESM and add to deps+scripts (npm run lint)
unit tests pass on node 14 and 18.

[dima11051994]

Thanks for this maintenance update! But since some of the changes are pretty major, specifically socket.io client update, I would suggest to bump the package version to 1.0.0. New socket client is incompatible with an old socket.io server 1.x and 2.x that is still running on many cloud nodes.

[joshperry]

No problem.

My primary concern was getting unit tests working to ensure the expected operation of the library with #13 and #15 pending. I made an assumption that you were either updating the cloud nodes or were going to start terminating these with a newer server version in the cloud for multisite since #13 is already updating socket-io to v4 with only a semver patch bump, with #15 also being based on it.

I'm fine making this a major bump, it just didn't seem to align with what was planned in these PRs.

Also, is there a target minimum node version that you guys need to support on the client side? I'd like to add that constraint to package.json.

[joshperry]

The reasoning for bumping the other deps was primarily around security concerns.