Add PHP 7.3 to Travis CI matrix, drop ancient libmemcached

Author: sodabrew

Diff for: .travis.yml

@@ -4,6 +4,7 @@ dist: trusty
 language: php
 php:
     - master
+    - 7.3
     - 7.2
     - 7.1
     - 7.0
@@ -17,7 +18,6 @@ env:
     - LIBMEMCACHED_VERSION=1.0.18 # Debian Jessie / Ubuntu Xenial
     - LIBMEMCACHED_VERSION=1.0.16 # RHEL / CentOS 7
     - LIBMEMCACHED_VERSION=1.0.8  # Debian Wheezy / Ubuntu Trusty
-    - LIBMEMCACHED_VERSION=1.0.2  # Ancient
 
 addons:
     apt: