[github] use 'textarea' for kernelversion

we want to render it as text (so accidental #<num> do not reference issues.
unfortunately, the 'input' type does not support a renderer

Author: umlaeute

.github/ISSUE_TEMPLATE/bug.yml

@@ -54,7 +54,7 @@ body:
       required: true
 
   - id: kernelversion
-    type: input
+    type: textarea
     attributes:
       label: kernel version
       description: |