Update PR template to reflect new Unity version

.github/pull_request_template.md

 # Peer Review Information:
 
 ## Editor / Package versioning:
-**Editor Version Target**: 2019.4
+**Editor Version Target**: 2020.3
 
 ## Dev Testing:
 **Tests Added**: 
 **At Risk Areas**: 
 
 ## Checklist
-- [ ] - Updated docs
-- [ ] - Updated changelog
-- [ ] - Updated test rail
+- [ ] Updated docs
+- [ ] Updated changelog
+- [ ] Updated test rail