GitHub Action to lint Python code

Prove the Python syntax errors as discussed in
* nmap#91
* nmap#342
* nmap#624
* nmap#665
* nmap#666
* nmap#1176
* nmap#1484
* nmap#1807
* nmap#1972
* nmap#2088 
* nmap#2279
* nmap#2287
* nmap#2446
* nmap#2493
* nmap#2522
And many more...

.github/workflows/lint_python.yml

@@ -0,0 +1,14 @@
+name: lint_python
+on: [pull_request, push]
+jobs:
+  lint_python:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: 3.11
+          cache: pip
+      - run: pip install --upgrade pip wheel
+      - run: pip install flake8
+      - run: flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics