Add PHP 7.4 to travis build matrix

Author: Xerkus

.travis.yml

@@ -44,6 +44,9 @@ matrix:
     - php: 7.3
       env:
         - DEPS=latest
+    - php: 7.4
+      env:
+        - DEPS=latest
 
 before_install:
   - if [[ $TEST_COVERAGE != 'true' ]]; then phpenv config-rm xdebug.ini || return 0 ; fi