Build/Test Tools: Trim the 4.9 workflows.

This trims the unit testing matrix to the highest and lowest supported version of each major PHP branch.

Props desrosj, johnbillion

See #64083


git-svn-id: https://develop.svn.wordpress.org/branches/4.9@61821 602fd350-edb4-49c9-b593-d223f7449a82

Author: johnbillion

.github/workflows/phpunit-tests.yml

@@ -45,7 +45,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest ]
-        php: [ '5.3', '5.4', '5.5' ]
+        php: [ '5.3' ]
         split_slow: [ false, true ]
         multisite: [ false, true ]
         memcached: [ false ]
@@ -77,18 +77,6 @@ jobs:
             memcached: false
             multisite: true
             split_slow: false
-          - php: '7.1'
-            phpunit: '6-php-7.1'
-            os: ubuntu-latest
-            memcached: false
-            multisite: false
-            split_slow: false
-          - php: '7.1'
-            phpunit: '6-php-7.1'
-            os: ubuntu-latest
-            memcached: false
-            multisite: true
-            split_slow: false
           - php: '7.0'
             phpunit: '6-php-7.0'
             os: ubuntu-latest