Replace deprecated imp module with importlib.

done as part of Python 3.12 spike (CURA-11078)

UM/PluginRegistry.py

@@ -1,11 +1,13 @@
-# Copyright (c) 2022 Ultimaker B.V.
+# Copyright (c) 2023 UltiMaker
 # Uranium is released under the terms of the LGPLv3 or higher.
 
-import imp
+import importlib.util
+import importlib.machinery
 import json
 import os
 import shutil  # For deleting plugin directories;
 import stat  # For setting file permissions correctly;
+import sys
 import time
 import types
 import zipfile
@@ -762,7 +764,10 @@ def _findPlugin(self, plugin_id: str) -> Optional[types.ModuleType]:
             except Exception:
                 pass
         try:
-            file, path, desc = imp.find_module(plugin_id, [final_location])
+            spec = importlib.machinery.PathFinder().find_spec(plugin_id, [final_location])
+            if len(spec.submodule_search_locations) != 1:
+                raise IndexError(f"Attempt to load plugin '{plugin_id}' from {len(spec.submodule_search_locations)} locations.")
+            path = spec.submodule_search_locations[0]
         except Exception:
             Logger.logException("e", "Import error when importing %s", plugin_id)
             return None
@@ -783,13 +788,12 @@ def _findPlugin(self, plugin_id: str) -> Optional[types.ModuleType]:
                 return None
 
         try:
-            module = imp.load_module(plugin_id, file, path, desc)  # type: ignore #MyPy gets the wrong output type from imp.find_module for some reason.
+            module = importlib.util.module_from_spec(spec)
+            sys.modules[plugin_id] = module
+            spec.loader.exec_module(module)
         except Exception:
             Logger.logException("e", "Import error loading module %s", plugin_id)
             return None
-        finally:
-            if file:
-                os.close(file) #type: ignore #MyPy gets the wrong output type from imp.find_module for some reason.
         self._found_plugins[plugin_id] = module
         return module