CI: Add Debian backports before updating

.ci/debian_install.sh

@@ -1,5 +1,13 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+# Source OS Release
+source /etc/os-release
+
+# When Debian add backports
+if [ "${ID}" == "debian" ]; then
+    echo "deb http://deb.debian.org/debian ${VERSION_CODENAME}-backports main" >> /etc/apt/sources.list
+fi
 
 # Install packages
 apt-get update -qq && \
-apt-get install -qq ${APT_INSTALL} checkinstall cmake dpkg-dev fakeroot g++ gcc qtbase5-dev qt5-qmake qttranslations5-l10n libqt4-dev libqt5svg5-dev
+apt-get install -qq ${APT_INSTALL} checkinstall cmake dpkg-dev fakeroot g++ gcc qtbase5-dev qt5-qmake qttranslations5-l10n libqt5svg5-dev