general: make time.tz.via_location user config lazy, move tests to my.tests package

also gets rid of the problematic reset_modules thingie

my/tests/common.py

@@ -1,7 +1,5 @@
 import os
 from pathlib import Path
-import re
-import sys
 
 import pytest
 
@@ -13,20 +11,6 @@ skip_if_not_karlicoss = pytest.mark.skipif(
 )
 
 
-def reset_modules() -> None:
-    '''
-    A hack to 'unload' HPI modules, otherwise some modules might cache the config
-    TODO: a bit crap, need a better way..
-    '''
-    to_unload = [m for m in sys.modules if re.match(r'my[.]?', m)]
-    for m in to_unload:
-        if 'my.pdfs' in m:
-            # temporary hack -- since my.pdfs migrated to a 'lazy' config, this isn't necessary anymore
-            # but if we reset module anyway, it confuses the ProcessPool inside my.pdfs
-            continue
-        del sys.modules[m]
-
-
 def testdata() -> Path:
     d = Path(__file__).absolute().parent.parent.parent / 'testdata'
     assert d.exists(), d