Clarify UnexpectedQuorum error message. (#4127)

## Motivation

If the validators voted for a different block than the client expected,
the error message doesn't make it clear what the hashes mean.

## Proposal

Clarify that they are block hashes.

## Test Plan

CI

## Release Plan

- Nothing to do / These changes follow the usual release cycle.

## Links

- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: afck

linera-core/src/client/mod.rs

@@ -1477,7 +1477,10 @@ pub enum ChainClientError {
     #[error(transparent)]
     BcsError(#[from] bcs::Error),
 
-    #[error("Unexpected quorum: got {hash}, {round}, expected {expected_hash}, {expected_round}")]
+    #[error(
+        "Unexpected quorum: validators voted for block {hash} in {round}, \
+         expected block {expected_hash} in {expected_round}"
+    )]
     UnexpectedQuorum {
         hash: CryptoHash,
         round: Round,