add ca-certs to the debian dependencies

source/downloads/index.html

@@ -29,6 +29,7 @@ platforms:
   install_commands: |
                     sudo dpkg -i gitlab-ce_7.10.1~omnibus.2-1_amd64.deb
   dependency_commands: |
+                    sudo apt-get install ca-certificates
                     sudo apt-get install openssh-server
                     sudo apt-get install postfix
 - name: debian8
@@ -37,6 +38,7 @@ platforms:
   install_commands: |
                     sudo dpkg -i gitlab-ce_7.10.1~omnibus.2-1_amd64.deb
   dependency_commands: |
+                      sudo apt-get install ca-certificates
                       sudo apt-get install openssh-server
                       sudo apt-get install postfix
 - name: centos6