Fix some imports mistakes

taiga/base/api/permissions.py

@@ -16,6 +16,8 @@
 
 import abc
 
+from functools import reduce
+
 from taiga.base.utils import sequence as sq
 from taiga.permissions.service import user_has_perm, is_project_owner
 from django.apps import apps

taiga/base/filters.py

@@ -13,8 +13,6 @@
 #
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-import operator
-from functools import reduce
 import logging
 
 from django.apps import apps