Add libmagic to docker image (#8895)

Author: norbusan

Dockerfile

@@ -10,7 +10,7 @@ RUN apk update && \
 # PDF Generation: weasyprint (libffi-dev jpeg-dev already included above)
 RUN apk add --virtual gdk-pixbuf-dev
 
-RUN apk --no-cache add postgresql-libs ca-certificates libxslt jpeg zlib file libxml2
+RUN apk --no-cache add postgresql-libs ca-certificates libxslt jpeg zlib file libxml2 libmagic
 # PDF Generation: weasyprint
 RUN apk --no-cache add cairo-dev pango-dev ttf-opensans