add_group_labels=true fails to create JIRA if any label value has a space

[twotired]

level=debug ts=2023-11-29T04:34:23.792222111Z caller=notify.go:426 msg=handleJiraErrResponse api=Issue.Create err="request failed. Please analyze the request body for more details. Status code: 400" url=https://jira.example.com/rest/api/2/issue
level=error ts=2023-11-29T04:34:23.79259245Z caller=main.go:180 msg="error handling request" statusCode=400 statusText="Bad Request" err="JIRA request https://jira.example.com/rest/api/2/issue returned status 400 , error \"request failed. Please analyze the request body for more details. Status code: 400\", body \"{\\\"errorMessages\\\":[],\\\"errors\\\":{\\\"labels\\\":\\\"The label 'reason=\\\\\\\"descriptive error message\\\\\\\"' contains spaces which is invalid.\\\"}}\"" receiver=jiralert groupLabels="unsupported value type"

Fixes could include:

1. skip labels with values that have invalid characters
2. replace invalid characters with '_'

	if r.conf.AddGroupLabels {
		for k, v := range data.GroupLabels {
			issue.Fields.Labels = append(issue.Fields.Labels, fmt.Sprintf("%s=%.200q", k, v))
		}
	}