fix: Update last_rcvd_timestamp in migration (#8434)

Fix https://github.com/chatmail/core/issues/8429

src/sql/migrations.rs

@@ -2487,6 +2487,24 @@ UPDATE msgs SET state=24 WHERE state=18; -- Change OutPreparing to OutFailed.
         .await?;
     }
 
+    inc_and_check(&mut migration_version, 157)?;
+    if dbversion < migration_version {
+        // Ensure that existing transports
+        // don't start out with last_rcvd_timestamp=0,
+        // so that they are not immediately deleted
+        sql.execute_migration_transaction(
+            |transaction| {
+                transaction.execute(
+                    "UPDATE transports SET last_rcvd_timestamp=?1 WHERE last_rcvd_timestamp=0",
+                    (tools::time(),),
+                )?;
+                Ok(())
+            },
+            migration_version,
+        )
+        .await?;
+    }
+
     let new_version = sql
         .get_raw_config_int(VERSION_CFG)
         .await?