Remove version cap for mysql-connector-python

live demo now runs on python 3.9.2 and so whatever issue i ran across
previously, is no longer a thing i guess.

maybe should officially declare python 3.9 classifier?  perhaps better
to add mysql version cap back in, for certain python versions?  for
now i'm feeling like just this is good enough

setup.py

@@ -76,17 +76,10 @@ extras = {
         # package                       # low                   high
 
         'invoke',                       # 1.4.1
+        'mysql-connector-python',
         'psycopg2',                     # 2.8.5
         'rattail[db,auth,bouncer]',     # 0.9.130
         'Tailbone',                     # 0.8.97
-
-        # we include mysql "always" even though it may not be actually needed
-        # TODO: must cap this for now, b/c it breaks CORE-POS integration?!
-        # (sometimes there are segfaults with basic grid queries)
-        # 'mysql-connector-python==8.0.17',
-        # TODO: was having trouble getting 8.0.17 to work on Ubuntu 20.04 with
-        # MySQL 8.0.21 and so am trying this out...
-        'mysql-connector-python',
     ],
 
     'catapult': [
@@ -106,9 +99,6 @@ extras = {
         #
         # package                       # low                   high
 
-        # TODO: this also is an experiment.  see notes above in 'app' extra.
-        # am still getting segfaults with 8.0.23 so this seems necessary
-        'mysql-connector-python==8.0.17',
         'pyCOREPOS',                    # 0.1.0
         'rattail-corepos',              # 0.1.0
         'tailbone-corepos',             # 0.1.1