Build/Test Tools: Add PHP7.3 RC1 to the build matrix

Currently, we need to do some extra steps to run 7.3, but this will help us with testing compatibility.

See: https://github.com/travis-ci/travis-ci/issues/9717

See #44771.


git-svn-id: https://develop.svn.wordpress.org/trunk@43673 602fd350-edb4-49c9-b593-d223f7449a82

.travis.yml

@@ -12,6 +12,14 @@ env:
     - WP_TRAVISCI=travis:phpunit
 matrix:
   include:
+  - php: 7.3.0RC1
+    sudo: required
+    dist: xenial
+    services: mysql
+    addons:
+      apt:
+        packages:
+          - libzip4
   - php: 7.2
     env: WP_TRAVISCI=travis:format
   - php: 7.1
@@ -33,6 +41,7 @@ matrix:
   - php: nightly
   allow_failures:
   - php: nightly
+  - php: 7.3.0RC1
 before_install:
 - |
   if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
@@ -66,7 +75,7 @@ before_script:
   # Install the specified version of PHPUnit depending on the PHP version:
   if [[ "$WP_TRAVISCI" == "travis:phpunit" ]]; then
     case "$TRAVIS_PHP_VERSION" in
-      7.2|7.1|7.0|nightly)
+      7.3.0RC1|7.2|7.1|7.0|nightly)
         echo "Using PHPUnit 6.x"
         travis_retry composer global require "phpunit/phpunit:^6"
         ;;