Your county will have animal control people who will be happy to come by for it. Alternatively, if you can entice a blacksnake to move into your garage, he'll kill it for you. Hoes work pretty well, too, if you can get to it with one.
A problem is that if one is nesting there, more may be present. They're usually loners in warmer months, so probably not this time of the year, but keep an eye out. You never know.