Configure minimum supported PHP version

Signed-off-by: Nathanael Esayeas <[email protected]>

Author: ghostwriter

composer.json

@@ -16,7 +16,13 @@
         "forum": "https://discourse.laminas.dev"
     },
     "config": {
-        "sort-packages": true
+        "sort-packages": true,
+        "platform": {
+            "php": "7.3.99"
+        },
+        "allow-plugins": {
+            "dealerdirect/phpcodesniffer-composer-installer": true
+        }
     },
     "extra": {
         "laminas": {