Add libmoosex-singleton-perl to {Build-,}Depends

| Error while loading /var/lib/jenkins/workspace/ngcp-panel-selenium/source/ngcp_panel.psgi: Can't locate MooseX/Singleton.pm in your Perl library.

debian/control

@@ -21,6 +21,7 @@ Build-Depends: debhelper (>= 8),
                libmoosex-fileattribute-perl,
                libmoosex-method-signatures-perl,
                libmoosex-object-pluggable-perl,
+               libmoosex-singleton-perl,
                libnamespace-sweep-perl,
                libperl5i-perl,
                libregexp-parser-perl,
@@ -55,6 +56,7 @@ Depends: libcatalyst-actionrole-acl-perl,
          libmoose-perl (>= 2.0~),
          libmoosex-fileattribute-perl,
          libmoosex-object-pluggable-perl,
+         libmoosex-singleton-perl,
          libnamespace-autoclean-perl,
          libnamespace-sweep-perl,
          libnet-http-perl,