filelock: ReadWriteLock on Windows acts on SQLite side files another local user places beside its database

filelock is a platform-independent file lock for Python. From 3.20.4 until 4.2.1, ReadWriteLock and AsyncReadWriteLock on Windows use _connect to attach SQLite to the lock database by pathname, allowing another local account that can create adjacent names to place a database-wal or database-journal side file before acquisition. An undeletable WAL file makes each read or write acquisition fail immediately with sqlite3.OperationalError regardless of timeout. Separately, when the database contains at least one table, a hot journal that grants the lock account modify rights can cause SQLite recovery to delete a file named by that journal only when the lock account has permission to delete the target. The issue requires a directory writable by another account, such as a shared Windows temporary directory, and does not affect private directories. This issue is fixed in version 4.2.1.