greg.tests: lower faker logging verbosity

The faker module spams the logs from test runs with needless messages
such as these:

	INFO:faker.factory:Provider `faker.providers.address` has been localized to `en_US`.
	INFO:faker.factory:Provider `faker.providers.automotive` has been localized to `en_US`.
	WARNING:faker.factory:Specified locale `en_US` is not available for provider `faker.providers.bank`. Locale reset to `en_GB` for this provider.

By lowering the test logging verbosity of this module in pytest's conftests.py,
we silence these.

Fixes: GREG-14

greg/tests/conftest.py

+import logging
+
+
+# faker spams the logs with localisation warnings
+# see https://github.com/joke2k/faker/issues/753
+logging.getLogger("faker").setLevel(logging.ERROR)