Run testsuite on PHP 7.4.

.travis.yml

@@ -5,6 +5,7 @@ php:
   - 5.6
   - 7.2
   - 7.3
+  - '7.4snapshot'
 
 dist: trusty
 
@@ -45,9 +46,15 @@ matrix:
     - php: 7.1
       env: CODECOVERAGE=1 DEFAULT=0
 
+  allow_failures:
+    - php: '7.4snapshot'
+
 before_install:
   - echo cakephp version && tail -1 VERSION.txt
-  - phpenv config-rm xdebug.ini
+  - |
+      if [[ ${TRAVIS_PHP_VERSION} != "7.4snapshot" ]]; then
+        phpenv config-rm xdebug.ini
+      fi
 
   - if [ $DB = 'mysql' ]; then mysql -u root -e 'CREATE DATABASE cakephp_test;'; fi
   - if [ $DB = 'mysql' ]; then mysql -u root -e 'CREATE DATABASE cakephp_test2;'; fi