Update funding.yml

Author: Scrum

.github/funding.yml

@@ -2,7 +2,7 @@
 
 github: # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
 patreon: posthtml
-open_collective: # Replace with a single Open Collective username
+open_collective: posthtml
 ko_fi: # Replace with a single Ko-fi username
 tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
 community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry