travis: update for changes in Git dependencies handling

Author: Benjamin Chrétien

.travis.yml

@@ -6,7 +6,7 @@ env:
   global:
   - APT_DEPENDENCIES="doxygen libltdl-dev libboost-all-dev liblog4cxx10-dev coinor-libipopt-dev libblas-dev liblapack-dev libmumps-seq-dev gfortran"
   - HOMEBREW_DEPENDENCIES="doxygen libtool boost log4cxx ipopt openblas mumps"
-  - GIT_DEPENDENCIES="roboptim/roboptim-core:dev"
+  - GIT_DEPENDENCIES="roboptim/roboptim-core;dev"
   - DEBSIGN_KEYID=5AE5CD75
   - PPA_URI="roboptim/ppa"
   - GH_USERNAME=thomas-moulard