chore(deps): update dependency google-cloud-storage to v2.6.0 (#520)

Co-authored-by: Dan Lee <[email protected]>

Author: renovate-bot

bookshelf/requirements.txt

@@ -1,6 +1,6 @@
 Flask==2.2.2
 google-cloud-firestore==2.7.2
-google-cloud-storage==2.5.0
+google-cloud-storage==2.6.0
 google-cloud-error-reporting==1.6.2
 google-cloud-logging==3.2.4
 gunicorn==20.1.0