Merge #2317

2317: Add pytz module to webdav container r=mergify[bot] a=ghostwheel42

## What type of PR?

bug-fix

## What does this PR do?

Get rid of radicale error "[ERROR] No module named 'pytz'"

### Related issue(s)
- closes #2315


Co-authored-by: Alexander Graf <ghostwheel42@users.noreply.github.com>

optional/radicale/Dockerfile

@@ -13,7 +13,7 @@ RUN apk add --no-cache \
 
 # Image specific layers under this line
 RUN apk add --no-cache curl \
- && pip3 install radicale~=3.0
+ && pip3 install pytz radicale~=3.0
 
 
 COPY radicale.conf /radicale.conf