Build: Add PHP 7.4 to the Travis build.

Travis have switched the nightly PHP version to PHP 8.0. The 7.4snapshot version is PHP 7.4.

We don't support 7.4 yet, so it's in allowed failures.

Fixes #46235.


git-svn-id: https://develop.svn.wordpress.org/trunk@44803 602fd350-edb4-49c9-b593-d223f7449a82

.travis.yml

@@ -16,6 +16,7 @@ matrix:
     env: WP_TRAVISCI=travis:format
   - php: 7.1
     env: WP_TRAVISCI=travis:js
+  - php: 7.4snapshot
   - php: 7.3
   - php: 7.2
   - php: 7.1
@@ -33,6 +34,7 @@ matrix:
     dist: precise
   - php: nightly
   allow_failures:
+  - php: 7.4snapshot
   - php: nightly
 before_install:
 - |
@@ -67,7 +69,7 @@ before_script:
   # Install the specified version of PHPUnit depending on the PHP version:
   if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
     case "$TRAVIS_PHP_VERSION" in
-      7.3|7.2|7.1|nightly)
+      7.4snapshot|7.3|7.2|7.1|nightly)
         echo "Using PHPUnit 7.x"
         travis_retry composer global require "phpunit/phpunit:^7"
         ;;