Add linting, including bandit, flake8 should error in near future

.github/workflows/test.yml

@@ -48,6 +48,17 @@ jobs:
         pip install wheel
         pip install -r requirements.txt
         python setup.py install
+    - name: Install additional python dependencies
+      if: ${{ matrix.python-version == '3.8' }}
+      run: |
+        pip install bandit flake8
+    - name: Lint
+      if: ${{ matrix.os == 'ubuntu-latest' && matrix.python-version == '3.8' }}
+      run: |
+        # stop the build if there are Python syntax errors or undefined names
+        flake8 pybitmessage --count --select=E9,F63,F7,F82 \
+        --show-source --statistics --exit-zero
+        bandit -r --exit-zero -x tests,bitmessagecurses -s B608 pybitmessage
     - name: Test
       run: |
         export PYTHONWARNINGS=all