Install runtime and test dependencies in exact-source journey CI

Assistant: codex
Assistant-Model: gpt-6.1-sol
Assistant-Session: 01a126e1-76f8-7643-8cf3-e93336539ade

.forgejo/workflows/journeys.yaml

@@ -2,13 +2,13 @@ name: Account journey acceptance
 on:
   push:
     branches: [main]
-    paths: ["src/**", "tests/**", "scripts/run_journey_suites.py", "Makefile", ".forgejo/workflows/journeys.yaml"]
+    paths: ["src/**", "tests/**", "scripts/run_journey_suites.py", "scripts/check_layer_conformance.py", "pyproject.toml", "Containerfile", "Makefile", ".forgejo/workflows/journeys.yaml"]
   workflow_dispatch:
 jobs:
   journeys:
     runs-on: ubuntu-latest
     container:
-      image: python:3.12-slim@sha256:d764629ce0ddd8c71fd371e9901efb324a95789d2315a47db7e4d27e78f1b0e9
+      image: python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1
     steps:
       - name: Test the exact commit
         run: |
@@ -17,7 +17,8 @@ jobs:
           python -c 'import os, urllib.request; urllib.request.urlretrieve("https://forgejo.coulomb.social/" + os.environ["GITHUB_REPOSITORY"] + "/archive/" + os.environ["GITHUB_SHA"] + ".tar.gz", "journey-source.tar.gz")'
           tar xzf journey-source.tar.gz -C journey-source --strip-components=1
           cd journey-source
-          PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=src python -m unittest discover -s tests
+          python -m pip install --no-cache-dir ".[runtime]" "pytest==8.4.2"
+          PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=src python -m pytest -q
           PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=src python scripts/check_layer_conformance.py --report
           PYTHONDONTWRITEBYTECODE=1 python scripts/run_journey_suites.py --report journey-report.json
           cat journey-report.json