move sparkplug protocol to js file as file is not included when packaging

maybe there is a better way to resolve this..

backend/src/Model/sparkplugb.ts

@@ -1,10 +1,9 @@
-import { readFileSync } from 'fs'
 import * as protobuf from 'protobufjs'
+import protocol from './sparkplugb.proto'
 import { Base64Message } from './Base64Message'
 import { Decoder } from './Decoder'
 
-const buffer = readFileSync(require.resolve('../../../../res/sparkplug_b.proto'))
-const root = protobuf.parse(buffer.toString()).root
+const root = protobuf.parse(protocol).root
 export let SparkplugPayload = root.lookupType('com.cirruslink.sparkplug.protobuf.Payload')
 
 export const SparkplugDecoder = {
@@ -18,5 +17,6 @@ export const SparkplugDecoder = {
     } catch {
       // ignore
     }
+    return undefined
   },
 }