fix: don't set mode option on workdir bind mount

runc v1.2+ checks that a bind mount definition doesn't have any
fs-specific options set on it, as these will not be applied.

We are erroneously setting `mode-777` on a `--workdir` bind mount prior
to this PR, so `--workdir` causes a failure where runc v1.2+ is
installed, and crun is not installed.

Remove the incorrect option. It likely came from a copy/paste of a
`tmpfs` definition, and has never been correct/effective here.

Fixes #3716

Author: dtrudg

internal/pkg/runtime/launcher/oci/mounts_linux.go

@@ -140,7 +140,6 @@ func (l *Launcher) addTmpMounts(mounts *[]specs.Mount) error {
 		opts := []string{
 			"rbind",
 			"relatime",
-			"mode=777",
 		}
 		if !l.cfg.AllowSUID {
 			opts = append(opts, "nosuid")