add MsgSource as el too (#7057)

* add MsgSource as el too

* lint

Author: agnxsh

beacon_chain/validators/validator_monitor.nim

@@ -1,5 +1,5 @@
 # beacon_chain
-# Copyright (c) 2021-2024 Status Research & Development GmbH
+# Copyright (c) 2021-2025 Status Research & Development GmbH
 # Licensed and distributed under either of
 #   * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
 #   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
@@ -212,6 +212,7 @@ type
     gossip = "gossip"
     api = "api"
     sync = "sync"
+    el = "el"
 
 template toGaugeValue(v: bool): int64 =
   if v: 1 else: 0