docs(PULL_REQUEST_TEMPLATE): add version upgrade

add version upgrade check, if a new feature is added

Author: racevedoo

PULL_REQUEST_TEMPLATE.md

@@ -9,4 +9,5 @@ Please describe why this PR should be merged here.
 - [ ] Code compiles correctly
 - [ ] Created tests which fail without the change (if possible)
 - [ ] All tests passing
+- [ ] Bump project version, if this adds a new feature
 - [ ] Extended the README / documentation, if necessary