tests: Do not set logging when loading gpt_test

We don't want to set logging when skipping the test case so it
cannot be defined on the module level.

tests/vmtests/gpt_test.py

@@ -14,8 +14,6 @@
 
 import parted
 
-set_up_logging()
-
 
 class GPTTestBase(VMBackedTestCase):
 
@@ -34,6 +32,12 @@ def __init__(self, *args, **kwargs):
         self.usrluks = None
         self.usr = None
 
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+
+        set_up_logging()
+
     def set_up_disks(self):
         disklabel.DiskLabel.set_default_label_type("gpt")