Revert "Also test on PHP 7.3"

This reverts commit d9ac86f.

php-cs-fixer is not ready yet for this :)

Author: stayallive

.travis.yml

@@ -11,7 +11,6 @@ php:
   - 7.0
   - 7.1
   - 7.2
-  - 7.3
 
 env:
   matrix:
@@ -38,8 +37,6 @@ matrix:
       env: LARAVEL=5.7.* TESTBENCH=3.7.* PHPUNIT=7.3.*
     - php: 7.2
       env: LARAVEL=5.0.* TESTBENCH=3.0.* PHPUNIT=4.8.*
-    - php: 7.3
-      env: LARAVEL=5.0.* TESTBENCH=3.0.* PHPUNIT=4.8.*
 
 before_install:
   - composer self-update --stable --no-interaction