blsforme/manager: Use more secure vfat mount options

We've now disabled automounting of ESP & XBOOTLDR in Serpent OS, so
to complement that change we use the same (more secure) vfat mount options
that systemd gpt autogenerate uses.

For moar securities.

Signed-off-by: Ikey Doherty <[email protected]>

blsforme/src/manager.rs

@@ -139,7 +139,7 @@ impl<'a> Manager<'a> {
     /// Mount an fat filesystem
     #[inline]
     fn mount_vfat_partition(&self, source: &Path, target: &Path) -> Result<ScopedMount, Error> {
-        let options: Option<&str> = None;
+        let options = Some("umask=0077,noexec,nosuid,nodev");
         if !target.exists() {
             create_dir_all(target)?;
         }