Setup dependabot to keep python 3rd parties dependencies up to date (such as platform.io)

Author: sebastienvermeille

.github/workflows/build.yml

@@ -22,6 +22,7 @@ jobs:
         uses: actions/setup-python@0b93645e9fea7318ecaed2b359559ac225c90a2b # v5.3.0
         with:
           python-version: '3.12'
+          cache: "pipenv"
 
       - name: Install pipenv
         run: |