fix(tests): Fix test case for Prometheus metrics

Disable prometheus multiprocess mode in tests to avoid global state:
Depending on the workers which are processing a testfile,
we might run into race issues where tests might influence each other.

We also need to make sure to clear any previously collected values
in case the same worker/process is executing different tests which
evaluate prometheus values.

Signed-off-by: moson <moson@archlinux.org>

test/test_metrics.py

@@ -8,7 +8,7 @@ from aurweb.models.user import User
 
 
 @pytest.fixture(autouse=True)
-def setup(db_test):
+def setup(db_test, prometheus_test):
     return