[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

openlibrary/plugins/upstream/borrow.py

@@ -1,6 +1,5 @@
 """Handlers for borrowing books"""
 
-import contextlib
 import copy
 import hashlib
 import hmac