remove branch deletion step (#160)

Author: achristmascarl

Makefile

@@ -59,7 +59,7 @@ release:
 	gh pr create --fill --label no-release-notes
 	gh pr diff | cat
 	@read -n 1 -p "are you sure you want to release v$(version)? [Y/n] " confirmation && if [ "$$confirmation" = "Y" ]; then echo " continuing..."; else echo " aborting..."; exit 1; fi
-	gh pr merge --admin --squash --delete-branch
+	gh pr merge --admin --squash
 	git checkout main
 	git pull
 	git tag "v$(version)" main