Fix icinga repository URL

Dockerfile

@@ -20,7 +20,7 @@ RUN groupadd -g 1000 jenkins \
 
 RUN curl https://packages.icinga.com/icinga.key | apt-key add - \
  && DIST=$(awk -F"[)(]+" '/VERSION=/ {print $2}' /etc/os-release) \
- && echo "deb http://packages.icinga.com/debian icinga-${DIST} main" > /etc/apt/sources.list.d/${DIST}-icinga.list
+ && echo "deb http://packages.icinga.com/raspbian icinga-${DIST} main" > /etc/apt/sources.list.d/${DIST}-icinga.list
 
 # Install build deps for Icinga 2 and Icinga Web 2
 RUN apt-get update \