clippy: Add an allow to work around a clippy bug

clippy in current stable thinks
  |(a, b)| (a, b)
is always the identity function, but due to match ergonomics, it might
be an implicit copy.

This is fixed in nightly by
  rust-lang/rust-clippy#11792

crates/tor-netdir/src/params.rs

@@ -601,6 +601,9 @@ mod test {
     }
 
     #[test]
+    // TODO remove when this upstream bug is fixed
+    ///  https://github.com/rust-lang/rust-clippy/issues/11764
+    #[allow(clippy::map_identity)]
     fn all_parameters() {
         use std::time::Duration;
         let mut p = NetParameters::default();