Move away from EOL Python versions for stack

[stucka]

Every project in this suite is keyed to Python 3.9, which is now completely EOL and already encountered one compatibility problem and a couple bug fixes for pipenv.

It's likely that shifting away will break more pieces of the suite, with documentation likely being one of the first to go.

• warn-github-flow
• warn-scraper
• warn-transformer
• WARN bot
• bln-python-client
• Github Actions -- upload-file
• Github Actions -- download file

[stucka]

Everything should be checked with safety scan at a minimum.

[stucka]

Perhaps should shift baseline to 3.14 for longer compatibility.