Install package in CI before running tests

Author: Arturo R Montesinos

.github/workflows/ci.yml

@@ -17,6 +17,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install ruff mypy pytest jsonschema
+          pip install -e .
 
       - name: Lint (Ruff)
         run: ruff check . && ruff format --check .