Stop testing unsupported Python 3.8 and 3.9 (again)

Either support Python 3.8 and 3.9 officially and keep testing these
versions, or stop testing. This grey area where you don't support
versions but still test them just in case doesn't help. For example,
ruff targets `requires-python` and generates code that may not be
compatible with earlier versions. Such code will break CI tests
with unsupported versions of Python.

Author: DimitriPapadopoulos

.github/workflows/tabulate.yml

@@ -8,8 +8,7 @@ jobs:
   build:
     strategy:
       matrix:
-        # Python 3.9 is not supported anymore, but it still works...
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
         os: ["ubuntu-latest", "windows-latest", "macos-latest"]
     runs-on: ${{ matrix.os }}