rust 1.53.0 updates (#2411)

## Issue Addressed

`make lint` failing on rust 1.53.0.

## Proposed Changes

1.53.0 updates

## Additional Info

I haven't figure out why yet, we were now hitting the recursion limit in a few crates. So I had to add `#![recursion_limit = "256"]` in a few places


Co-authored-by: realbigsean <seananderson33@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>

common/validator_dir/src/builder.rs

@@ -231,7 +231,7 @@ impl<'a> Builder<'a> {
                 if self.store_withdrawal_keystore {
                     // Write the withdrawal password to file.
                     write_password_to_file(
-                        password_dir.join(withdrawal_keypair.pk.to_hex_string()),
+                        password_dir.join(withdrawal_keypair.pk.as_hex_string()),
                         withdrawal_password.as_bytes(),
                     )?;