Remove unused bitcell-crypto dependency

Based on code review feedback, removed the bitcell-crypto dependency
as it was not actually used in the governance crate. All tests still pass.

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

Author: Copilot

crates/bitcell-governance/Cargo.toml

@@ -8,7 +8,6 @@ license.workspace = true
 repository.workspace = true
 
 [dependencies]
-bitcell-crypto = { path = "../bitcell-crypto" }
 serde.workspace = true
 thiserror.workspace = true
 bincode.workspace = true