Update test_stable.yml

.github/workflows/test_stable.yml

@@ -59,6 +59,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
     - name: Install dependencies
       run: |
+        pip install setuptools  # Needed for next line on Python 3.12.
         python setup.py egg_info
         req_txt="botorch.egg-info/requires.txt"
         min_torch_version=$(grep '\btorch[>=]=' ${req_txt} | sed 's/[^0-9.]//g')