ci(pytest.yml): introduce github action on ubuntu

This commit aims to provide an automated testing with pytest moderated
by GitHub actions.  Its scope is constrained twice -- both for pytest,
as well as for the testing operating system -- to familiarize

1) how to file a PR to project I don't own which however now allows
   me to admit a PR.
2) To learn if in this situation a contributor can set GitHub actions
   in a repository owned by an other user.

Signed-off-by: Norwid Behrnd <nbehrnd@yahoo.com>

.github/workflows/pytest.yml

@@ -0,0 +1,37 @@
+name: CI_pytest_appendfilename
+
+# name    : pytest.yml
+# purpose : regularly run pytest on appendfilename
+# date    : [2024-10-31 Thu]
+# edit    :
+
+on:
+  push:
+    branches:
+      - master           # additions to the principal branch "master"
+  pull_request:
+    branches:
+      - master           # PRs to enter the principal branch "master"
+  workflow_dispatch:     # provide a manual trigger
+  # schedule:
+    # - cron: "0 0 1 * *"  # once each 1st of a month, at 00:00 UTC (cf. https://crontab.guru/)
+
+jobs:
+  test-ubuntu:
+    runs-on: ubuntu-24.04
+    timeout-minutes: 2
+
+    steps:
+      - uses: actions/checkout@v4
+        # by [2024-10-23 Wed], this version possibly will be considered "old", cf.
+        # https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+
+      - name: Install dependencies with PyPI
+        run: pip install -r requirements.txt
+
+      - name: run the check by pytest
+        run: python -m pytest