Test without sqlalchemy-citext

[cjmayo]

The last sqlalchemy-citext update was in 2021 and it has various compatibility issues.

SQLAlchemy now has CITEXT support.

[cjmayo]

Whether this is case sensitive and whether we are testing it I am unsure:

flask-admin/flask_admin/contrib/sqla/form.py

Line 323 in 5b069be

@converts('Text', 'LargeBinary', 'Binary', 'CIText') # includes UnicodeText

[cjmayo]

Added a new commit - a wider problem - doesn't look like we have been testing SQLAlchemy 1.

With use_frozen_constraints constraints are generated by calling "pip
freeze" after the environment deps have been installed and before the
package dependencies are installed, thus constraints-sqlalchemy1.txt is
being ignored.

An idea of how to fix it in the added commit. At least this was all I could find. N.B. the formatted output of the GitHub Actions can truncate the list of pip installed packages.

[cjmayo]

I'll rebase after #2540.

[cjmayo]

Rebased.

[cjmayo]

Finished experimenting.

[samuelhwilliams]

This looks sensible. Would you mind adding an entry in doc/changelog.rst under a new v2.0.0a2 heading please?

[cjmayo]

Rebase this one? doc/changelog.rst has updated since.