Update PR template

Author: fabpot

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,6 @@
 | Q             | A
 | ------------- | ---
-| Branch?       | 7.1 for features / 5.4, 6.4, or 7.0 for bug fixes <!-- see below -->
+| Branch?       | 7.2 for features / 5.4, 6.4, 7.0, and 7.1 for bug fixes <!-- see below -->
 | Bug fix?      | yes/no
 | New feature?  | yes/no <!-- please update src/**/CHANGELOG.md files -->
 | Deprecations? | yes/no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->