[Build Error] Fail to build at step 6 (postgres_browser)

[MQasking]

when i try to get your project from docker,i meet the question i don't know how to do. what should i do?please help .
the error is :

Step 6/29 : RUN echo "deb http://packages.dotdeb.org  squeeze all" >> /etc/apt/sources.list.d/dotdeb.org .list && 	echo "deb-src http://packages.dotdeb.org  squeeze all" >> /etc/apt/sources.list.d/dotdeb.org .list && 	wget -O- http://www.dotdeb.org/dotdeb.gpg  | apt-key add ----> Running in 332002fc783c
--2018-03-10 13:12:25--  http://www.dotdeb.org/dotdeb.gpg Resolving www.dotdeb.org  (www.dotdeb.org )... E: gnupg, gnupg2 and gnupg1 do not seem to be installed, but one of them is required for this operation
195.154.242.153 , 2001:bc8:21eb:100::1
Connecting to www.dotdeb.org  (www.dotdeb.org)|195.154.242.153|:80 ... connected.
HTTP request sent, awaiting response... 200 OK
Length: 5299 (5.2K) [application/octet-stream]
Saving to: 'STDOUT'

     0K                                                         0% 0.00 =0s


Cannot write to '-' (Broken pipe).
ERROR: Service 'postgres_browser' failed to build: The command '/bin/sh -c echo "deb http://packages.dotdeb.org  squeeze all" >> /etc/apt/sources.list.d/dotdeb.org .list && 	echo "deb-src http://packages.dotdeb.org  squeeze all" >> /etc/apt/sources.list.d/dotdeb.org .list && 	wget -O- http://www.dotdeb.org/dotdeb.gpg  | apt-key add -' returned a non-zero code: 255

[luckydonald]

Retrying the build can solve network hiccups.

Otherwise, you'll might need to update and fix the install commands in the Dockerfile

[jiayuanyuan67777]

what should I do? Please help.