CI: fix container build

Containerfile

@@ -1,10 +1,14 @@
 # Build: podman build -t code.philo.ydns.eu/philorg/tinyseady-mailer -f Containerfile
 
-FROM docker.io/python:3.12-alpine
+FROM docker.io/python:3.13-alpine
+RUN apk add --no-cache git 
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/
 
-COPY . /src
-WORKDIR /src
-RUN uv sync --frozen --no-cache && uv pip install --system .
+COPY . /app
+
+# Sync the project into a new environment, using the frozen lockfile
+WORKDIR /app
+
+RUN uv pip install --system .
 
 CMD tinysteady-mailer