CI: pymysql 0.8.0 compat

[jreback]

revert this: #19461

[jreback]

cc @jorisvandenbossche @TomAugspurger @gfyoung

[jorisvandenbossche]

So the failures are for the tests with procedures (test_read_procedure). Might be related to:

* **BACKWARD INCOMPATIBLE** ``MULTI_STATEMENTS`` client flag is no longer
  set by default, while it was on PyMySQL 0.7.  You need to pass
  ``client_flag=CLIENT.MULTI_STATEMENTS`` when you connect to explicitly
enable multi-statement mode. (#590)

from their changelog notes https://github.com/PyMySQL/PyMySQL/blob/master/CHANGELOG