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>

crypto/bls/src/generic_public_key.rs

@@ -51,7 +51,7 @@ where
     }
 
     /// Returns `self.serialize()` as a `0x`-prefixed hex string.
-    pub fn to_hex_string(&self) -> String {
+    pub fn as_hex_string(&self) -> String {
         format!("{:?}", self)
     }
 

crypto/bls/src/generic_public_key_bytes.rs

@@ -70,7 +70,7 @@ impl<Pub> GenericPublicKeyBytes<Pub> {
     }
 
     /// Returns `self.serialize()` as a `0x`-prefixed hex string.
-    pub fn to_hex_string(&self) -> String {
+    pub fn as_hex_string(&self) -> String {
         format!("{:?}", self)
     }