Do not allow failures under PHP 7.1.

jmalloc · jmalloc · commit 80d114c88ce3 · 2017-10-18T07:31:40.000+10:00
diff --git a/.travis.yml b/.travis.yml
@@ -7,7 +7,6 @@ php:
 matrix:
   fast_finish: true
   allow_failures:
-  - php: '7.1'
   - php: nightly
 before_install:
 - phpenv config-rm xdebug.ini || true
