feat!: upgrade mocha to v9, node support to 16+

[TobiTenno]

v10 drops node 12 support

[TobiTenno]

@filipedeschamps we either have to drop node < 14 support, or stop updating this dependency. which is a bigger problem, do you think?

[TobiTenno]

@filipedeschamps would appreciate your thoughts

[filipedeschamps]

We can drop, but need to release a major version 🤝

[TobiTenno]

for sure, I agree there. thankfully that would be automated with semantic-release

[TobiTenno]

@filipedeschamps could you:

• update the merge requirements to add 18, 20, 22, 24; and remove 8, 12, & 14?
• move this to its own org? like rss-feed-emitter as the org & repo name so you could give me more management perms so i could manage these things?
• set up OIDC on the package on https://npmjs.com/package/rss-feed-emitter/settings and/or add me as a collaborator so i can also help with those parts

[TobiTenno]

@filipedeschamps poking you again to see if you can update the merge reqs at least