Use latest zope.sqlalchemy package

session / transaction registration modified per upstream changes, but
previous logic kept to support older versions of zope.sqlalchemy - for
now, although probably should require minimum version soon?

setup.py

@@ -62,11 +62,6 @@ requires = [
     #
     # package                           # low                   high
 
-    # TODO: previously was capping this to pre-1.0 although i'm not sure why.
-    # however the 1.2 release has some breaking changes which require refactor.
-    # cf. https://pypi.org/project/zope.sqlalchemy/#id3
-    'zope.sqlalchemy<1.2',              # 0.7                   1.1
-
     # TODO: apparently they jumped from 0.1 to 0.9 and that broke us...
     # (0.1 was released on 2014-09-14 and then 0.9 came out on 2018-09-27)
     # (i've cached 0.1 at pypi.rattailproject.org just in case it disappears)
@@ -106,6 +101,7 @@ requires = [
     'waitress',                         # 0.8.1
     'WebHelpers2',                      # 2.0
     'WTForms',                          # 2.1
+    'zope.sqlalchemy',                  # 0.7                   2.0
 ]