Fix keysign (#12)

* Retrieve aptly pubkey from website

Co-authored-by: Wellyas <[email protected]>

Dockerfile

@@ -35,7 +35,7 @@ RUN apt-get -q update \
     gettext-base \
     bash-completion
 
-RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ED75B5A4483DA07C \
+RUN curl -sL https://www.aptly.info/pubkey.txt | gpg --dearmor | tee /etc/apt/trusted.gpg.d/aptly.gpg >/dev/null \
   && echo "deb http://repo.aptly.info/ squeeze main" >> /etc/apt/sources.list
 
 # Install aptly package