Install git in the translate step's container

translate.py shells out to git (rev-list, diff, add, commit, push) to
find changed *.es.md files and push translated siblings back, but the
python:3.12-slim image the translate step runs in doesn't include the
git binary, so the pipeline failed immediately with:
FileNotFoundError: [Errno 2] No such file or directory: 'git'

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NizVpJ2dwzCbjCrTLCjeHn

.woodpecker.yml

@@ -26,6 +26,9 @@ steps:
       GITEA_PUSH_TOKEN:
         from_secret: gitea_push_token
     commands:
+      # translate.py shells out to git (rev-list/diff/add/commit/push) — the
+      # slim image doesn't ship it.
+      - apt-get update -qq && apt-get install -qq -y --no-install-recommends git
       - pip install --quiet requests pyyaml
       - python scripts/translate.py