ci: Add action to publish main docs on pushes

[joseemds]

Fixes #23

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This PR adds an action that when some code i pushed into main (this include merged pull requests) it will do the same checks that the release action does (this is actually the release action copied, but the version file is generated in a different way) and if everything goes right, it will publish a release to hexdocs using the format <next-version>-dev (where is the current version with a minor dump).

PS: mix format --check-formatted is failing, but this PR doesnt change any file rather then adding the action file, should i run mix format ?

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Before submitting the PR make sure the following are checked:

• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Wrote good commit messages.
• Feature branch is up-to-date with main (if not - merge main into your branch).
• Added tests.
• Ran mix check.all, it verifies the formatting and runs credo and dialyzer
• Ran mix test
• Added an entry to the Changelog if the new code introduces user-observable changes. See the changelog entry format.