re-vendor "editor"

[zzzeek]

the python-editor package now has a deprecation warning:

DeprecationWarning: The distutils package is deprecated and slated for removal in Python 3.12. Use setuptools or check PEP 632 for potential alternatives

project looks to be not maintained since 2019: https://github.com/fmoo/python-editor

a newer package looks to be maintained but has lots of dependencies (two) for what is like a ten line program: https://github.com/rec/editor

this "editor" concern is very trivial and not worth relying upon these come-and-go ten line packages out there so I suggest we re-vendor this. our original impl can be seen in 7b91b32,

[sqla-tester]

CaselIT has proposed a fix for this issue in the master branch:

Revendor editor and make dateutil optional https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/2872