PR #8299 second review requested

Hi all — following up on PR #8299 ( Raise ValueError in blob_dog when min_sigma <= 0 by ravikumar266 · Pull Request #8299 · scikit-image/scikit-image · GitHub ), a small bug-fix for blob_dog crashing on min_sigma <= 0. It received approval from @fallenmi about a week ago and all CI checks are green. Looking for a second review whenever someone has bandwidth. Thanks!