CI: install setuptools before dev deps to support legacy http-ece build

http-ece (pulled in by pywebpush) uses setup.py and requires setuptools,
which is not included in the deadsnakes Python 3.12 install.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.forgejo/workflows/ci.yml

@@ -86,6 +86,9 @@ jobs:
           apt-get install -y -qq python3.12 python3.12-dev python3.12-venv python3-pip git
           python3.12 -m ensurepip --upgrade
 
+      - name: Install setuptools (required by legacy deps)
+        run: python3.12 -m pip install setuptools
+
       - name: Install package with dev deps
         run: python3.12 -m pip install -e ".[dev]"