Update bug report template to follow the new bug report process

* Severity instead of Priority
* Bug instead of Report

Ref: https://projects.blender.org/infrastructure/blender-projects-platform/issues/118

.gitea/issue_template/bug.yaml

@@ -1,9 +1,9 @@
 name: Bug Report
 about: Use Help > Report a Bug from the top of Blender to automatically fill out part of this form.
 labels:
-  - "Type/Report"
+  - "Type/Bug"
   - "Status/Needs Triage"
-  - "Priority/Normal"
+  - "Severity/Normal"
 body:
   - type: markdown
     attributes: