don't use ambient authority

Signed-off-by: Gareth Widlansky <gareth.widlansky@proton.me>

Author: Gareth Widlansky

crates/lib/src/bootloader.rs

@@ -4,7 +4,6 @@ use std::process::Command;
 use anyhow::{anyhow, bail, Context, Result};
 use bootc_utils::CommandRunExt;
 use camino::Utf8Path;
-use cap_std_ext::cap_std::ambient_authority;
 use cap_std_ext::cap_std::fs::Dir;
 use cap_std_ext::dirext::CapStdExtDirExt;
 use fn_error_context::context;
@@ -102,7 +101,9 @@ pub(crate) fn install_systemd_boot(
             let path = esp_path.join(SYSTEMD_AUTOENROLL);
             create_dir_all(&path)?;
 
-            let keys_dir = Dir::open_ambient_dir(&path, ambient_authority())
+            let keys_dir = esp_mount
+                .fd
+                .open_dir(SYSTEMD_AUTOENROLL)
                 .with_context(|| format!("Opening {path}"))?;
             for filename in keys.iter() {
                 let p = path.join(filename.clone());