chore(ci): make install script be on one line

Author: Kent C. Dodds

.travis.yml

@@ -13,8 +13,7 @@ install:
   - npm install
   # as requested by the React team :)
   # https://reactjs.org/blog/2019/10/22/react-release-channels.html#using-the-next-channel-for-integration-testing
-  - if [ "$TRAVIS_EVENT_TYPE" = "cron" ]; then npm install react@next
-    react-dom@next; fi
+  - if [ "$TRAVIS_EVENT_TYPE" = "cron" ]; then npm install react@next react-dom@next; fi
 script: npm run validate
 after_success: kcd-scripts travis-after-success
 branches: