Drop long EOL versions in favor of PHP5.6+

.travis.yml

@@ -1,12 +1,7 @@
 language: php
 
-# We require precise here, as 5.3 doesn't exist on trusty.
-dist: precise
-
 php:
-  - 5.3
   - 5.6
-  - 7.0
   - 7.3
   - 7.4snapshot
 
@@ -22,13 +17,10 @@ services:
 matrix:
   fast_finish: true
   include:
-    - php: 5.3
-      env: DB=mysql PHPUNIT=4.8.35
-
-    - php: 5.4
+    - php: 5.6
       env: DB=pgsql
 
-    - php: 5.5
+    - php: 7.0
       env: DB=sqlite
 
     - php: 7.3