Revert "feat: update Python version requirements to 3.12 in workflow and setup"

This reverts commit 30a21a4.

Author: devincowan

.github/workflows/test-on-pr.yml

@@ -14,7 +14,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: [3.12]
+        python-version: [3.9]
         platform: [ubuntu-latest]
 
     runs-on: ${{ matrix.platform }}

setup.py

@@ -30,7 +30,7 @@
     author='Scott Black',
     author_email='scott.black@usu.edu',
     description='A python client for managing HydroShare resources',
-    python_requires='>=3.12',
+    python_requires='>=3.9',
     long_description=README,
     long_description_content_type="text/markdown",
     classifiers=[