chore(NODE-6426): update saslprep dependency to 1.1.9 (#4327)

Author: durran

package-lock.json

@@ -25,7 +25,7 @@
     "email": "[email protected]"
   },
   "dependencies": {
-    "@mongodb-js/saslprep": "^1.1.5",
+    "@mongodb-js/saslprep": "^1.1.9",
     "bson": "^6.10.0",
     "mongodb-connection-string-url": "^3.0.0"
   },