agent: Allow clippy::question_mark warning in Namespace{}

As the rust toolchain version bump to its 1.66.0 release raised a
warning about the code being able to be refactored to use `?`.

For now that's something we don't need to change, so let's ignore such
warning in this very specific case.

See:
https://rust-lang.github.io/rust-clippy/master/index.html#question_mark

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

src/agent/src/namespace.rs

@@ -78,6 +78,7 @@ impl Namespace {
     // setup creates persistent namespace without switching to it.
     // Note, pid namespaces cannot be persisted.
     #[instrument]
+    #[allow(clippy::question_mark)]
     pub async fn setup(mut self) -> Result<Self> {
         fs::create_dir_all(&self.persistent_ns_dir)?;