Update .travis.yml

.travis.yml

@@ -29,7 +29,6 @@ env:
   - TARGET=Mars.target
   - TARGET=Neon.target
   - TARGET=Oxygen.target
-  - TARGET=Photon.target
 before_script:
  - wget https://github.com/google/googletest/archive/release-1.8.0.zip
  - unzip release-1.8.0.zip