test: Increase timeout to 10 seconds (MR 113)

The tests seem to be randomly timing out in CI after the gitlab
migration, so let's increase the timeout.

test/pytest.ini

@@ -3,7 +3,7 @@ addopts = --strict-markers
 markers =
     skip_ci
     img_dir_gen
-timeout = 3
+timeout = 10
 
 # Kill all threads on timeout
 timeout_method = thread