block pypy for now
block pypy for now

the most recent pypy 7.3.8 series (3.7 and 3.9 included, likely
3.8 as well) have installed a 9 year old version of SQLite,
and additionally seem to have some other behavioral changes
like formatting of exception messages that is breaking
some tests.  as we are waiting on a response at [1]
remove pypy testing for now.

[1] https://foss.heptapod.net/pypy/pypy/-/issues/3690

Change-Id: I66650635111e71241b5c45a778954544c8d2490e

zzzeek/sqlalchemy,sqlalchemy/sqlalchemy