Fix release process

[mattkjames7]

Description

Refactor workflows:

• Deduplicate build and test workflows: keep build-and-test.yml, remove build-packages.yml'. The build-packages.yml` tested the actual installed package, now that is an added step in each Ubuntu build.
• Remove build-docs.yml -> now the docs are built by the prepare-release.yml workflow.
• Updated all actions to their latest versions and referenced them by SHA.
• New prepare-release.yml workflow which runs the tests for each supported Python version in Ubuntu, updates the changelog and the version in pyproject.toml and creates a PR to be reviewed before merging.
• Once prepare-release.yml has ran, and the PR merged, we can run the release.yml workflow to make the source package and upload to PyPI; deploy the docs and create the GitHub release + tag.

Pull request type

Please delete options that are not relevant.

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring with functional or API changes
• Refactoring without functional or API changes
• Build or packaging related changes
• Documentation content changes
• Other (please describe):

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

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Reviewer checklist (the reviewer checks this part)

• Core feature implementation
• Tests
• Code documentation
• Documentation on gqlalchemy/docs

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[antejavor]

Nice 🚀