remove mkdocs not used

Updated actions versions and Python command usage.

Author: tomkralidis

.github/workflows/main.yml

@@ -11,16 +11,15 @@ jobs:
     name: Test JSON artifact generation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@master
+      - uses: actions/setup-python@v5
         with:
           python-version: '3.x'
       - name: Install requirements 📦
         run: |
           python -m pip install --upgrade pip
-          pip install mkdocs
       - name: Run ⚙️
         run: |
-          python -mjson.tool live-deployments.geojson
-          python -mjson.tool community/psc.geojson
+          python3 -mjson.tool live-deployments.geojson
+          python3 -mjson.tool community/psc.geojson