maint: bump xterm and xterm-addon-fit

[consideRatio]

This PR bumps the package.json's dependencies and devDependencies. Since we don't have a package-lock.json, the ^ means that in practice we are using the latest major version before and after this change for all packages except for those listed below. I've manually read through these changelogs and searched our code base for something breaking without finding anything.

dependencies:

• xterm, from v4 to v5, related docs
• xterm-addon-fit, from 0.5 to 0.7, related docs same as xterm above
• Unchanged: bootstrap, see #1395

devDependencies:

• eslint, from v7 to v8, related docs
• babel-loader, from v8 to v9, related docs
• webpack-cli, from v4 to v5, related docs

---

• Test failure unrelated, reported in #1656

[manics]

Have you already manually verified the UI works (https://binderhub.readthedocs.io/en/latest/contribute.html#develop-user-interface) or does this still need to be checked?

[consideRatio]

No, I'll check!

[consideRatio]

Thanks @manics for helping me test this easily!

I've verified things look as usual:

• in the main view with the form allowing users to input what repo to build/launch
• in the "clicked a link to launch directly" view

The failure seen is because I've not started a jupyterhub to launch etc, but the terminal looks fine and like before.

[consideRatio]

Thanks for the review @manics and @sgibson91!!