Ditch Travis CI

[magical]

Travis-ci.org stopped doing builds as of June 2021. We could theoretically migrate to travis-ci.com but from what i've heard they've severely restricted their free support for open source projects (thanks, bitcoin miners) and it doesn't seem worth the hassle given that we have Github Actions now.

• Delete travis.yml
• Remove the webhooks they added

[itsjavi]

you could migrate to Github Actions

[magical]

@itsjavi Yes, we already have GitHub actions set up.