fixed ci docker image build issue;

updated docker image to alpine 3.14;
pinned certbot version

Dockerfile

@@ -1,22 +1,14 @@
-FROM python:3.9-alpine3.13 as build-image
+FROM alpine:3.14
 
-RUN apk add --no-cache gcc musl-dev libffi-dev openssl-dev cargo
-
-RUN python3 -m venv /opt/venv
-ENV PATH="/opt/venv/bin:$PATH"
+RUN apk add --no-cache python3 py3-pip py3-cryptography
 
 WORKDIR /certbot_dns_duckdns
 
-COPY build-requirements.txt build-requirements.txt
-RUN pip install -r build-requirements.txt
+COPY docker-build-requirements.txt docker-build-requirements.txt
+RUN pip install -r docker-build-requirements.txt
 
 COPY . .
 
 RUN pip install .
 
-FROM python:3.9-alpine3.13
-
-COPY --from=build-image /opt/venv /opt/venv
-ENV PATH="/opt/venv/bin:$PATH"
-
 ENTRYPOINT ["certbot"]

build-requirements.txt → docker-build-requirements.txt

@@ -1,3 +1,3 @@
 requests>=2.20.0
-certbot>=1.7.0
+certbot==1.16.0
 zope.interface>=5.0.0