Revert "prevent zero networkID (#9763)" (#9815)

This reverts commit 73f08b3.

Author: ordian

json/src/spec/params.rs

@@ -35,7 +35,6 @@ pub struct Params {
 
 	/// Network id.
 	#[serde(rename="networkID")]
-	#[serde(deserialize_with="uint::validate_non_zero")]
 	pub network_id: Uint,
 	/// Chain id.
 	#[serde(rename="chainID")]
@@ -209,20 +208,4 @@ mod tests {
 
 		let _deserialized: Params = serde_json::from_str(s).unwrap();
 	}
-
-	#[test]
-	#[should_panic(expected = "a non-zero value")]
-	fn test_non_zero_network_id() {
-		let s = r#"{
-			"maximumExtraDataSize": "0x20",
-			"networkID" : "0x0",
-			"subprotocolName" : "exp",
-			"minGasLimit": "0x1388",
-			"accountStartNonce": "0x01",
-			"gasLimitBoundDivisor": "0x20",
-			"maxCodeSize": "0x1000"
-		}"#;
-
-		let _deserialized: Params = serde_json::from_str(s).unwrap();
-	}
 }