update actions to skip bib testing for python < 3.9

.github/workflows/python-app.yaml

@@ -48,10 +48,13 @@ jobs:
         python -m pip install --upgrade pip setuptools wheel
         pip install pytest pytest-cov flake8
 
-    # install package & dependencies
     - name: Install package and dependencies
-      run: |
-        pip install .[bib]
+      if: ${{ python-version < 3.9 }}
+      run: pip install .
+
+    - name: Install package and dependencies
+      if: ${{ python-version >= 3.9 }}
+      run: pip install .[bib]
 
     # linting & pytest
     - name: Lint with flake8

tests/test_esupy.py

@@ -1,5 +1,7 @@
 """Test functions"""
 
+import pytest
+import sys
 from pathlib import Path
 
 import esupy.processed_data_mgmt as es_dt
@@ -25,6 +27,8 @@ def test_data_commons_access():
 
     assert(df1 is not None and df2 is None)
 
+
+@pytest.mark.skipif(sys.version_info < (3, 9), reason="bibliographies require python3.9 or higher")
 def test_source_generation():
     source_list = bibtex.generate_sources(
         bib_path = Path(__file__).parents[1] / 'tests' / 'test.bib',