upgrade travis to webpack 4 beta 1

Author: johnnyreilly

.travis.yml

@@ -7,7 +7,7 @@ install:
   - yarn add $WEBPACK $TSLOADER $VUELOADER -D
 # Test against multiple webpack versions
 env:
-  - WEBPACK=webpack@^4.0.0-beta.0 TSLOADER=ts-loader@^4.0.0-beta.0 VUELOADER=vue-loader@^14.1.0
+  - WEBPACK=webpack@^4.0.0-beta.1 TSLOADER=ts-loader@^4.0.0-beta.0 VUELOADER=vue-loader@^14.1.0
   - WEBPACK=webpack@^3.10.0 TSLOADER=ts-loader@^3.4.0 VUELOADER=vue-loader@^13.5.0
   - WEBPACK=webpack@^2.7.0 TSLOADER=ts-loader@^3.4.0 VUELOADER=vue-loader@^13.5.0
 deploy: