Update Travis build matrix. Since WordPress 5.2, the minimum required PHP version is 5.6. Older builds failing as expected, let's exclude them.

Author: Shawn Hooper

.travis.yml

@@ -1,35 +1,34 @@
 sudo: false
 language: php
 php:
-  - 5.4
-  - 5.5
   - 5.6
   - 7.0
   - 7.1
   - 7.2
+  - 7.3
 env:
   - WP_VERSION=latest
   - WP_VERSION=4.5
 dist: trusty
 matrix:
   include:
     - php: 5.2
-      env: WP_VERSION=latest
-      dist: precise
-    - php: 5.2
-      env: WP_VERSION=4.5
+      env: WP_VERSION=5.1
       dist: precise
     - php: 5.3
-      env: WP_VERSION=latest
+      env: WP_VERSION=5.1
       dist: precise
-    - php: 5.3
-      env: WP_VERSION=4.5
+    - php: 5.4
+      env: WP_VERSION=5.1
+      dist: precise
+    - php: 5.5
+      env: WP_VERSION=5.1
       dist: precise
-    - php: 5.6
+    - php: 7.3
       env: WP_VERSION=latest WP_MULTISITE=1
-    - php: 5.6
+    - php: 7.3
       env: WP_VERSION=4.5 WP_MULTISITE=1
-    - php: 7.0
+    - php: 7.3
       env: NPM_TESTS=1
 
 before_script: