Update FUNDING.yml

Author: AlbertMN

.github/FUNDING.yml

@@ -10,4 +10,4 @@ liberapay: # Replace with a single Liberapay username
 issuehunt: # Replace with a single IssueHunt username
 otechie: # Replace with a single Otechie username
 custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']
-custom: ['https://www.paypal.me/albermn']
+custom: 'https://www.paypal.me/albermn'