rclone: Incomplete path validation allows backend root escape in serve restic

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.40.0 until 1.75.0, rclone serve restic does not correctly reject URL paths beginning with ../ in cmd/serve/restic/restic.go WithRemote, which accepts a leading parent path and passes it to GET, HEAD, POST, and DELETE handlers for configured backends including WebDAV, FTP, HTTP, Memory, and SFTP. An attacker who can access the REST endpoint may read, create, overwrite, or delete objects outside the path configured by the operator when the operator publishes a backend subdirectory and the backend credential can access parent or sibling objects. This issue is fixed in 1.75.0.