support webhooks created after 22/7/2022

this PR fixes the webhook url regex for webhooks created after 22/7/2022.

[x] Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
[x] Ensure that the pull request title represents the desired changelog entry
[x] Please describe what you did
[ ] Link to relevant issues in GitHub or Jira
[ ] Link to relevant pull requests, esp. upstream and downstream changes
[ ] Ensure you have provided tests - that demonstrates feature works or fixes the issue

jenkinsci / discord-notifier-plugin