Update version numbers

Author: markstory

.github/ci.yml

@@ -1,4 +1,4 @@
-
+---
 name: CI
 
 on:
@@ -15,10 +15,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php-version: ['5.6', '7.2', '7.4', '8.0']
+        php-version: ['5.6', '7.4', '8.0']
         prefer-lowest: ['']
         include:
-          - php-version: '7.2'
+          - php-version: '5.6'
             prefer-lowest: 'prefer-lowest'
 
     steps:
@@ -59,7 +59,7 @@ jobs:
 
     - name: Run PHPUnit
       run: |
-        if ${{ matrix.php-version == '5.6' }}; then
+        if [[ ${{ matrix.php-version }} == '5.6']]; then
           vendor/bin/phpunit tests/php56/
         else
           vendor/bin/phpunit