Test release CI within PR

[pedro-psb]

This PR does:

• re-organize script to (mostly based on the old release.sh)
  • bump version-files + update changelog
  • build and sanity-check distribution
  • create release commit
• proper setup git on CI to be able to push the commit-release
• output relevant information for debugging

Other notes:

• I've temporarily added 'on: pull_request` to the release workflow so I can fix all the CI small details without having to merge to master to test. Also, this is still "dry-run" mode.
• I'll uncomment the final steps (that actually commit and publish) once the PR is good

[netlify]

✅ Deploy Preview for dynaconf ready!

Name	Link
🔨 Latest commit	de914c5
🔍 Latest deploy log	https://app.netlify.com/sites/dynaconf/deploys/65c903e250864a00087bc16e
😎 Deploy Preview	https://deploy-preview-1050--dynaconf.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d64540d) 98.80% compared to head (de914c5) 98.80%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1050   +/-   ##
=======================================
  Coverage   98.80%   98.80%           
=======================================
  Files          23       23           
  Lines        2257     2257           
=======================================
  Hits         2230     2230           
  Misses         27       27           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[pedro-psb]

Replaced by #1078