Fix Travis CI trying to build Pico 3.0 on PHP 5.x

.travis.yml

@@ -10,14 +10,6 @@ cache:
 jobs:
   include:
     # Test stage
-    - php: 5.3
-      dist: precise
-    - php: 5.4
-      dist: trusty
-    - php: 5.5
-      dist: trusty
-    - php: 5.6
-      dist: xenial
     - php: 7.0
       dist: xenial
     - php: 7.1
@@ -25,15 +17,14 @@ jobs:
     - php: 7.3
     - php: 7.4
     - php: nightly
-    - php: hhvm-3.24 # until Dec 2018
     - php: hhvm-3.27 # until Sep 2019
     - php: hhvm-3.30 # until Nov 2019
 
     # Branch deployment stage
     - stage: deploy-branch
       if: type == "push" && tag IS blank
-      php: 5.3
-      dist: precise
+      php: 7.0
+      dist: xenial
       install:
         - '[[ ",$DEPLOY_PHPDOC_BRANCHES," == *,"$TRAVIS_BRANCH",* ]] || travis_terminate 0'
         - install.sh --deploy
@@ -43,8 +34,8 @@ jobs:
     # Release deployment stage
     - stage: deploy-release
       if: tag IS present
-      php: 5.3
-      dist: precise
+      php: 7.0
+      dist: xenial
       install:
         - install.sh --deploy
       script: