add composer json

composer.json

@@ -0,0 +1,11 @@
+{
+    "name": "d3data/empty",
+    "description": "no description",
+    "keywords": [],
+    "type": "library",
+    "license": "LGPL-3.0",
+    "require": {
+        "php": "^7.3|^8.0",
+        "ext-mbstring" : "*"
+    }
+}