chore(clippy): fix or_fun_call lint

https://rust-lang.github.io/rust-clippy/master/index.html#/or_fun_call

Author: notmandatory

crates/bdk/src/wallet/mod.rs

@@ -1506,7 +1506,7 @@ impl<D> Wallet<D> {
                 });
             let current_height = sign_options
                 .assume_height
-                .or(self.chain.tip().map(|b| b.height()));
+                .or_else(|| self.chain.tip().map(|b| b.height()));
 
             debug!(
                 "Input #{} - {}, using `confirmation_height` = {:?}, `current_height` = {:?}",

crates/bitcoind_rpc/src/lib.rs

@@ -90,7 +90,7 @@ impl<'c, C: bitcoincore_rpc::RpcApi> Emitter<'c, C> {
             .last_mempool_tip
             // We use `start_height - 1` as we cannot guarantee that the block at
             // `start_height` has been emitted.
-            .unwrap_or(self.start_height.saturating_sub(1));
+            .unwrap_or_else(|| self.start_height.saturating_sub(1));
 
         // Mempool txs come with a timestamp of when the tx is introduced to the mempool. We keep
         // track of the latest mempool tx's timestamp to determine whether we have seen a tx