ci: install checked out OctoPrint

Author: foosel

.github/workflows/build.yml

@@ -51,7 +51,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ["3.7", "3.12"]
+        python: ["3.12"]
     steps:
       - name: "⬇ Checkout OctoPrint with E2E tests"
         uses: actions/checkout@v4
@@ -73,8 +73,9 @@ jobs:
           python-version: ${{ matrix.python }}
 
       - name: 🏗 Install OctoPrint
+        working-directory: ./OctoPrint/
         run: |
-          pip install OctoPrint
+          pip install .
           pip install --force-reinstall ${{ github.workspace }}/dist/*.whl
 
       - name: 🏗 Create base config for test server