Drop wallet lock before sleeping and retrying

.. no need to keep the wallet locked if we're sleeping. So we're
dropping and re-locking.

src/wallet.rs

@@ -107,14 +107,18 @@ where
 			Err(e) => match e {
 				bdk::Error::Esplora(ref be) => match **be {
 					bdk::blockchain::esplora::EsploraError::Reqwest(_) => {
+						// Drop lock, sleep for a second, retry.
+						drop(wallet_lock);
 						tokio::time::sleep(Duration::from_secs(1)).await;
 						log_error!(
 							self.logger,
 							"Sync failed due to HTTP connection error, retrying: {}",
 							e
 						);
 						let sync_options = SyncOptions { progress: None };
-						wallet_lock
+						self.inner
+							.lock()
+							.unwrap()
 							.sync(&self.blockchain, sync_options)
 							.await
 							.map_err(|e| From::from(e))