Update Python support to reflect dependency update

Python 3.8 end of support is in October of 2024.  However, some projects
`case-utils` includes in its dependencies, most recently NumPy, are
ending their support for Python 3.8 ahead of this EOL.

This patch removes 3.8 from the test base, so updates for imported
packages continue to be retrieved retrieved.

References:
* #127

Signed-off-by: Alex Nelson <alexander.nelson@nist.gov>

.github/workflows/cicd.yml

@@ -36,7 +36,7 @@ jobs:
     strategy:
       matrix:
         python-version: 
-          - '3.8'
+          - '3.9'
           - '3.11'
 
     steps:

setup.cfg

@@ -25,7 +25,7 @@ install_requires =
     requests
     tabulate
 packages = find:
-python_requires = >=3.8
+python_requires = >=3.9
 
 [options.entry_points]
 console_scripts =