deps: update to libpathrs v0.2.5

This update includes a few breaking API changes that I needed to get in
before an actual runc release depends on it, so that we don't need to
deal with compatibility shims for them (or bumping the SOVERSION).

From a Go API perspective, there were no major changes -- though this
bump did also require a bump to github.com/cyphar/filepath-securejoin
because one of the wrapped APIs changed from int to uint64 as a flag
argument type. Again, better to get this done before we really depend on
this in a public way.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

vendor/github.com/cyphar/filepath-securejoin/pathrs-lite/open_libpathrs.go

@@ -53,5 +53,5 @@ func Reopen(file *os.File, flags int) (*os.File, error) {
 	}
 	defer handle.Close() //nolint:errcheck // close failures aren't critical here
 
-	return handle.OpenFile(flags)
+	return handle.OpenFile(uint64(flags))
 }