Add secondary fix for PHP7.3

Author: szepeviktor

example/.travis.yml

@@ -0,0 +1,3 @@
+install:
+  - |
+    if [ "$(phpenv version-name)" == 7.3 ]; then sed -e 's#^function is_countable(#// &#' -i vendor/giacocorsiglia/wordpress-stubs/wordpress-stubs.php; fi

example/phpstan.neon.dist

@@ -32,3 +32,4 @@ parameters:
         - '/^Parameter #2 \$deprecated of function load_plugin_textdomain expects string, false given\.$/'
         # WP-CLI accepts a class as callable
         - '/^Parameter #2 \$callable of static method WP_CLI::add_command\(\) expects callable\(\): mixed, \S+ given\.$/'
+        # Please consider commenting ignores: issue URL or reason of ignore