Update all dependencies of WCFS to their recent versions:

• go-fuse: update to pick up https://github.com/hanwen/go-fuse/commit/265a3926 and https://github.com/hanwen/go-fuse/commit/90b055af. The first patch potentially improves performance, while the second fixes support for neo:// with multiple masters.
• go123: add support for go1.20
• testify: some bugfixes (we use this package only during tests)

The following dependencies were not updated by upstream at all:

• glog
• overflow
• ogórek
• pkg/errors

.

/cc @levin.zimmermann