remove "pylons" app template for 1.8

[zzzeek]

this template is from decades ago from the old pre-pyramid form of pylons and is certainly not functional, for example it refers to "wsgi_app" that isn't even created in the default case.

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the main branch:

remove pylons template https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/3886