fix not a package type error for importlib (#193)

* fix not a package type error for importlib

* [pre-commit.ci] auto fixes from pre-commit hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/diffpy/pdfgui/gui/pdfguiglobals.py

@@ -30,7 +30,11 @@
 isAltered = False
 
 # Resolve APPDATADIR base path to application data files.
-_mydir = os.path.abspath(str(files(__name__)))
+try:
+    _mydir = os.path.abspath(str(files(__name__)))
+except TypeError:  # For Python < 3.12
+    _mydir = os.path.abspath(os.path.dirname(__file__))
+
 _upbasedir = os.path.normpath(_mydir + "/../../..")
 _development_mode = os.path.basename(_upbasedir) == "src" and os.path.isfile(
     os.path.join(_upbasedir, "../pyproject.toml")