Use 'slug' label in new pattern issue template

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: brunoborges

.github/ISSUE_TEMPLATE/new-pattern.yml

@@ -2,7 +2,7 @@
 name: New Pattern Submission
 description: Submit a new modern Java pattern
 title: "[Pattern] "
-labels: ["new-pattern"]
+labels: ["slug"]
 body:
   - type: markdown
     attributes: