Update PHP 7.3

Author: filipsedivy

composer.json

@@ -23,7 +23,7 @@
         }
     ],
     "require": {
-        "php": "^7.1",
+        "php": "^7.3",
         "ext-curl": "*",
         "ext-dom": "*",
         "ext-openssl": "*",
@@ -46,6 +46,9 @@
     "minimum-stability": "dev",
     "prefer-stable": true,
     "config": {
-        "sort-packages": true
+        "sort-packages": true,
+        "platform": {
+            "php": "7.3"
+        }
     }
 }