Moved setup-php to correct location

.github/workflows/php.yml

@@ -1,10 +1,5 @@
 name: PHPUnit Tests
 
-uses: shivammathur/setup-php@2.11.0
-with:
-  php-version: '7.3'
-  extensions: 'xdebug'
-
 on:
   push:
     branches: [ main ]
@@ -17,6 +12,11 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
+    - uses: shivammathur/setup-php@2.11.0
+      with:
+        php-version: '7.3'
+        extensions: 'xdebug'
+        
     - uses: actions/checkout@v2
 
     - name: Validate composer.json and composer.lock