Revert "Remove caching"

This reverts commit 162988f.

Author: delfanbaum

.github/workflows/workflow.yaml

@@ -25,6 +25,17 @@ jobs:
           virtualenvs-in-project: true
           installer-parallel: true
 
+      - name: Load cached venv if possible
+        id: cached-poetry-dependencies
+        uses: actions/cache@v2
+        with:
+          path: .venv
+          key: venv-${{ runner.os }}-${{ steps.setup-python.outputs.python-version }}-${{ hashFiles('**/poetry.lock') }}
+
+      - name: Install dependencies if needed
+        if: steps.cached-poetry-dependencies.outputs.cache-hit != 'true'
+        run: poetry install --no-interaction --no-root
+
       - name: Install Project
         run: poetry install --no-interaction