docs(travis): change deploy docs script on travis

Author: fernandogelin

.travis.yml

@@ -30,8 +30,8 @@ matrix:
       os: linux
       julia: 1.1
       script:
-        - julia -e 'import Pkg; Pkg.instantiate(); Pkg.add("Documenter"); include(joinpath("docs", "make.jl"))'
-
+        - julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
+        - julia --project=docs/ docs/make.jl
     # - stage: semantic release
     #   if: branch = master AND type != pull_request
     #   language: python