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

also gets rid of the problematic reset_modules thingie

tests/orgmode.py

@@ -1,10 +1,9 @@
 from my.tests.common import skip_if_not_karlicoss as pytestmark
 
-from my import orgmode
-from my.core.orgmode import collect
-
-
 def test() -> None:
+    from my import orgmode
+    from my.core.orgmode import collect
+
     # meh
     results = list(orgmode.query().collect_all(lambda n: [n] if 'python' in n.tags else []))
     assert len(results) > 5