pkp/pkp-lib#9733 Add luxon dependency

Author: jardakotesovec

package-lock.json

@@ -32,6 +32,7 @@
     "jquery": "^3.7.1",
     "jquery-ui": "^1.14.1",
     "jquery-validation": "~1.21.0",
+    "luxon": "^3.5.0",
     "moment": "^2.30.1",
     "ofetch": "^1.4.1",
     "pinia": "^2.3.1",