Corrected environment variables for Travis CI

Author: gnongsie

.travis.yml

@@ -2,31 +2,42 @@ language: php
 
 sudo: false
 
-env:
-    - TEST_SUITE=samples
-
 matrix:
   include:
     - php: 5.6
-      env: PHPUNIT_VERSION=5.6.*
+      env: 
+        - PHPUNIT_VERSION=5.6.*
+        - TEST_SUITE=samples
       dist: trusty
     - php: 7.0
-      env: PHPUNIT_VERSION=5.6.*
+      env: 
+        - PHPUNIT_VERSION=5.6.*
+        - TEST_SUITE=samples
       dist: trusty
     - php: 7.1
-      env: PHPUNIT_VERSION=5.7.*
+      env: 
+        - PHPUNIT_VERSION=5.7.*
+        - TEST_SUITE=samples
       dist: trusty
     - php: 7.2
-      env: PHPUNIT_VERSION=8.5.*
+      env: 
+        - PHPUNIT_VERSION=8.5.*
+        - TEST_SUITE=samples
       dist: bionic
     - php: 7.3
-      env: PHPUNIT_VERSION=9.5.*
+      env: 
+        - PHPUNIT_VERSION=9.5.*
+        - TEST_SUITE=samples
       dist: bionic
     - php: 7.4
-      env: PHPUNIT_VERSION=9.5.*
+      env: 
+        - PHPUNIT_VERSION=9.5.*
+        - TEST_SUITE=samples
       dist: bionic
     - php: 8.0
-      env: PHPUNIT_VERSION=9.5.*
+      env: 
+        - PHPUNIT_VERSION=9.5.*
+        - TEST_SUITE=samples
       dist: bionic
 
 before_install: