Revert "require php-sap/datetime #5"

This reverts commit 7bbed21.

Author: gregor-j

Diff for: composer.json

@@ -22,8 +22,7 @@
   "minimum-stability": "stable",
   "require": {
     "php": "^5.5|^7.0|^8.0",
-    "ext-json": "*",
-    "php-sap/datetime": "^1.3"
+    "ext-json": "*"
   },
   "autoload": {
     "psr-4": {