Update .travis.yml

Author: juan-pablo-vielma

.travis.yml

@@ -19,8 +19,8 @@ sudo: required
 
 # Before anything else, get the latest versions of things
 before_script:
-  - julia -e 'using Pkg; Pkg.add(url="https://github.com/JuliaPackaging/BinaryProvider.jl")'
-  - julia -e 'using Pkg; Pkg.add(url="https://github.com/JuliaPackaging/BinaryBuilder.jl"); Pkg.build()'
+  - julia -e 'using Pkg; Pkg.add(PackageSpec(url="https://github.com/JuliaPackaging/BinaryProvider.jl"))'
+  - julia -e 'using Pkg; Pkg.add(PackageSpec(url="https://github.com/JuliaPackaging/BinaryBuilder.jl")); Pkg.build()'
 
 script:
   - julia build_tarballs.jl