Merge master into 0.2 branch

I agreed with @mark that I shoud tag current HEAD with a new tag (0.2.9) which we can use for openappstacks 0.6.0 release (https://open.greenhost.net/openappstack/openappstack/-/issues/837). This MR merges current master head into the 0.2 branch.

consent_provider/Dockerfile

-FROM python:3.7-alpine
+FROM python:3.9-alpine
 
 RUN apk add gcc libc-dev libffi-dev