use standard project layout and tool config across all pallets and
pallets-eco projects
* add issue templates
* add dependabot grouped updates for actions and pypi
* add lock inactive closed issues workflow
* add publish workflow with slsa and trusted publishing
* simplify tests workflow matrix
* simplify docs config.py
* show license in docs
* use pip-compile to pin development dependencies
* rename test to tests
* add .editorconfig
* simplify .gitignore
* add pre-commit hooks (will run formatters in a subsequent PR)
* pin os and python in .readthedocs.yaml
* update license with original commit date and pallets-eco
* use pyproject.toml and flit_core instead of setuptools
* only declare flask dependency
* add config for mypy and pyright (will add typing in a subsequent PR)
* readme is markdown
* add pallets-eco message to readme
* remove install and docs links from readme
* add style, typing, docs tox envs
* use faster wheel building tox config
* add tox command to update dev dependencies
Require Flask >= `2.2.0`.
I'm comfortable going up to requiring `3.x`, but when I grep'd for
places we use older Flask constructs, this was all I found.
So for now no need to jump further.
Flask `2.2.0` requires Python >= `3.7`, so also dropped older pythons.
* Remove the branch constraint for pull request triggering
* Use Python 3.12 for main tests
* Use `ubuntu-20.04` for Python 3.6 since it's been removed in `ubuntu-latest`
* Remove Python 2.7 since it's not supported by GitHub Actions anymore (https://github.com/actions/setup-python/issues/672)
* Add the missing `setup-python` step
* Merge the `pip install` commands
