PR template: fix target update list

Not only new target, any target update goes to own section. This covers
target updates to SDK, HAL implementation, target list, etc.
All these go to patch releases.

Author: 0xc0170

.github/pull_request_template.md

@@ -18,7 +18,7 @@
 -->
     [ ] Fix
     [ ] Refactor
-    [ ] New target
+    [ ] Target update
     [ ] Feature
     [ ] Breaking change