Refactor GitHub Actions workflow to support multiple Python versions

Signed-off-by: Myrausman <maira.usman5703@gmail.com>

.github/workflows/python-app.yml

@@ -9,25 +9,36 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.6, 3.8, latest]
+
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python 3.8
+
+    - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v2
       with:
-        python-version: 3.8
+        python-version: ${{ matrix.python-version }}
+
     - name: Install PyYAML
       run: |
         pip3 install -r requirements.txt
         pip3 install coverage
+
     - name: Run pre-commit
       run: |
         python3 -m pip install pre-commit
         pre-commit run --all-files
+
     - name: Generate
       run: coverage run ./parse.py -c -chisel -sverilog -rust -latex -spinalhdl -go "rv*" "unratified/rv*"
+
     - name: Check C output
-      run: cat encoding.out.h  | cpp
+      run: cat encoding.out.h | cpp
+
     - name: Generate coverage
       run: coverage xml
+
     - name: Upload coverage
       uses: codecov/codecov-action@v2