make docker image build work

- Depend on a python version Debian actually ships with in
  pyproject.toml and update the poetry.lock accordingly.
- Fix poetry bundle complaining about no python by installing
  python-is-python3.
  Also remove the python flag for poetry bundle then.

Dockerfile

@@ -1,12 +1,12 @@
 FROM docker.io/library/debian:12-slim AS builder
 RUN apt-get update && \
-    apt-get install --no-install-suggests --no-install-recommends --yes pipx
+    apt-get install --no-install-suggests --no-install-recommends --yes pipx python-is-python3
 ENV PATH="/root/.local/bin:${PATH}"
 RUN pipx install poetry
 RUN pipx inject poetry poetry-plugin-bundle
 WORKDIR /src
 COPY . .
-RUN poetry bundle venv --python=/usr/bin/python3 --only=main /venv
+RUN poetry bundle venv --only=main /venv
 
 FROM gcr.io/distroless/python3-debian12
 COPY --from=builder /venv /venv

poetry.lock

@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 1.8.2 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.8.4 and should not be changed by hand.
 
 [[package]]
 name = "humanize"
@@ -26,5 +26,5 @@ files = [
 
 [metadata]
 lock-version = "2.0"
-python-versions = "^3.12"
-content-hash = "0b022231d09549e564a7cec69a9169cbd5a27e550b5a10a8b57ef2bbe251b6fe"
+python-versions = "^3.11"
+content-hash = "bc794458508ceedfc18e9635ad18b7113d5118c414698ebc12762c782ed3670d"

pyproject.toml

@@ -6,7 +6,7 @@ authors = ["Stefan Bethke <stb@lassitu.de>"]
 readme = "README.md"
 
 [tool.poetry.dependencies]
-python = "^3.12"
+python = "^3.11"
 pgsql = "^2.2"
 humanize = "^4.9.0"