failfs: OpenFile() returns a typed nil file on error

Fix file methods on a type nil file

avfs: Fix VolumeNameLen go:linkname for Go versions >= 1.23

avfs: Rename tag datarace to avfs_race

avfs: Update goreleaser-action to v4

avfs: Fix readme.md

Clone() is replaced by Sub("/")

ci: Run build tests on linux only

avfs: Manage umask for all operating systems

avfs: Move OrefaFS.splitPath to avfs.SplitAbs

avfs: Perform CodeQL analysis daily

orefafs: Fix Rename for Windows