pull from keppel and update to python 3.11

Dockerfile

@@ -1,8 +1,10 @@
-FROM python:3.6-alpine as base
+FROM keppel.eu-de-1.cloud.sap/ccloud-dockerhub-mirror/library/python:3.11-alpine as base
 FROM base as builder
 
-RUN apk add --update --no-cache --virtual build-deps gcc python3-dev musl-dev libc-dev linux-headers libxslt-dev libxml2-dev \
-&& apk add libffi-dev openssl-dev 
+RUN apk update \
+    && apk upgrade \
+    && apk add --update --no-cache --virtual build-deps gcc python3-dev musl-dev libc-dev linux-headers libxslt-dev libxml2-dev \
+    && apk add libffi-dev openssl-dev 
 RUN python -m pip install --upgrade pip
 
 RUN mkdir /install
@@ -11,9 +13,13 @@ COPY requirements.txt /requirements.txt
 RUN pip3 install --prefix="/install" -r /requirements.txt
 
 FROM base
-LABEL source_repository="https://github.com/sapcc/ironic_exporter"
+
 COPY --from=builder /install /usr/local
+
 COPY src /app
 WORKDIR /app
 
+LABEL source_repository="https://github.com/sapcc/ironic_exporter"
+LABEL maintainer="Bernd Kuespert <[email protected]>"
+
 CMD ["python", "main.py"]