remove unused build-tools revision

Author: hawkrives

.travis.yml

@@ -38,7 +38,6 @@ matrix:
           - build-tools-23.0.1
           - build-tools-23.0.2
           - build-tools-25.0.1
-          - build-tools-23.0.3
           - build-tools-25.0.2
           - build-tools-25.0.3
           - build-tools-26.0.1
@@ -103,7 +102,7 @@ before_install:
       nvm install "$TRAVIS_NODE_VERSION";
       nvm use "$TRAVIS_NODE_VERSION";
     fi
-  
+
   - echo "node -v is now $(node -v)"
 
   # turn off fancy npm stuff