update composer lock hash

Author: gregor-j

composer.json

@@ -20,7 +20,7 @@
     "php": "^5.5|^7.0",
     "ext-json": "*",
     "php-sap/interfaces": "^2.0",
-    "php-sap/datetime": "^1.1"
+    "php-sap/datetime": "^1.2"
   },
   "autoload": {
     "psr-4": {