Make PicardTestCase the parent class of all tests

This brings the faketagger and, more importantly, settings reset to all of them.

test/test_api_helpers.py

@@ -1,4 +1,4 @@
-import unittest
+from test.picardtestcase import PicardTestCase
 from unittest.mock import MagicMock
 
 from picard import config
@@ -9,9 +9,10 @@ from picard.webservice.api_helpers import (
 )
 
 
-class APITest(unittest.TestCase):
+class APITest(PicardTestCase):
 
     def setUp(self):
+        super().setUp()
         self.host = "abc.com"
         self.port = 80
         self.api_path = "/v1/"
@@ -43,7 +44,7 @@ class APITest(unittest.TestCase):
         self._test_ws_function_args(self.ws.delete)
 
 
-class MBAPITest(unittest.TestCase):
+class MBAPITest(PicardTestCase):
 
     def setUp(self):
         self.config = {'server_host': "mb.org", "server_port": 443}