update-plugin-list: use json, use http caching, use gh action caches

this change
* switches from html index usage to json index usage
* adds using requests-cache as http cache to trim down runtime
* adds gh action caches for pip and the new http cache

Author: RonnyPfannschmidt

.github/workflows/update-plugin-list.yml

@@ -27,12 +27,20 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v4
         with:
-          python-version: 3.8
+          python-version: "3.8"
+          cache: pip
+      - name: requests-cache
+        uses: actions/cache@v3
+        with:
+          path: ~/.cache/pytest-plugin-list/
+          key: plugins-http-cache-${{ github.run_id }} # Can use time based key as well
+          restore-keys: plugins-http-cache-
 
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install packaging requests tabulate[widechars] tqdm
+          pip install packaging requests tabulate[widechars] tqdm requests-cache platformdirs
+
 
       - name: Update Plugin List
         run: python scripts/update-plugin-list.py