Replace find_module function

find_module function was deprecated in Python 3.4 [1] and later removed
in Python 3.12 [2], the find_spec function should be used instead. This
change is necessary for proper Python 3.12 support.

[1] https://docs.python.org/3.4/library/importlib.html#importlib.abc.MetaPathFinder.find_module
[2] python/cpython#98040

Change-Id: I8354918d6548192dea3492eb2ee682d323559912
Signed-off-by: Petr Vaněk <arkamar@atlas.cz>

oslotest/modules.py

@@ -45,6 +45,6 @@ class _NoModuleFinder(object):
     def __init__(self, module):
         self.module = module
 
-    def find_module(self, fullname, path):
+    def find_spec(self, fullname, path, target):
         if fullname == self.module or fullname.startswith(self.module + '.'):
             raise ImportError