Add TODO comments about possibly migrating away from the backtrace crate.

crates/arti/src/logging.rs

@@ -261,8 +261,9 @@ fn install_panic_handler() {
             .map(|loc| loc.to_string().into())
             .unwrap_or_else(|| "???".into());
 
+        // TODO MSRV 1.65: std::backtrace::Backtrace is stable; maybe we should be using
+        // that instead?
         let backtrace = backtrace::Backtrace::new();
-
         tracing::error!("Panic at {}: {}\n{:?}", location_str, msg, backtrace);
     }));
 }

crates/tor-error/src/internal.rs

@@ -10,6 +10,8 @@ use super::*;
 /// Backtrace implementation for when the feature is enabled
 mod ie_backtrace {
     use super::*;
+    // TODO MSRV 1.65: std::backtrace::Backtrace is stable; maybe we should be
+    // using that instead?
     use backtrace::Backtrace;
 
     #[derive(Debug, Clone)]