Test on Windows PHP 5.4 too (#63)

Author: GrahamCampbell

.github/workflows/tests.yml

@@ -52,7 +52,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
+        php: ['5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
 
     steps:
       - name: Configure Git