build: disable documention on xapian for travis-ci. --disable-documentation passed to configure doesn't work and I have a crash in sphinx that prevents testing. Use -enable-documentation=no which appears to be how 1.4.14 expects it at least. no-github-ci to disable testing for github as this change affects travis only at this point. If it works, I'll disable doc build on github to to save cycles.

# human timezones
pytz
# indexer
Whoosh
# xapian is also installed
# extra database support
psycopg2
mysqlclient
redis
# encryption
gpg
# java web tokens
PyJWT
# extra HTTP compression methods
Brotli
zstd
# jinja2 template engine
Jinja2