Go demo SpotAccountInfo results in "Signature for this request is not valid"

[confleux]

Description
I've needed to test signature generation for GET /api/v3/account endpoint. Running mexc-api-demo/go/run demo/Spot Trade results in an error: {"code":700002,"msg":"Signature for this request is not valid."}

Steps to Reproduce

1. Set up API keys in config/config.go
2. Make request: go run /run demo/Spot Trade/SpotAccountInfo.go

Actual behavior
Response is: {"code":700002,"msg":"Signature for this request is not valid."}

Expected behavior
Response is {"makerCommission":null, ..., "permissions":["SPOT"]}

Additional context
I've resolved the error for this endpoint.

mexc-api-demo/go/utils/utils.go

Line 54 in 83f5b76

message := fmt.Sprintf("%s&timestamp=%d", strParams, timestamp)

Changing to this resolved an error:

message := fmt.Sprintf("%stimestamp=%d", strParams, timestamp)

This fix works for GET /api/v3/account, but further testing needed for other endpoints.