FieldsValue need more types to be accepted

## What happened?
I am trying to create an issue in ServiceDesk that is set up on-premise.
Am getting a an error of:
```golang
{"time":"2023-10-23T16:28:52.746847979+03:00","level":"INFO","msg":"request failed. Please analyze the request body for more details. Status code: 400"}
```
I am may be going wrong about it but I am see in a manual approach a ticket I created from the UI and using curl/firefox to see the ticket I see:
```json
{
"fieldId": "customfield_29695",
"label": "Jira project",
"value": {
"self": "https://jira.REDACTED.net/jira/rest/api/2/project/16910",
"id": "16910",
"key": "AT",
"name": "Foo Bar Paz",
"projectTypeKey": "service_desk",
"avatarUrls": {
"48x48": "https://jira.REDACTED.net/jira/secure/projectavatar?pid=16910&avatarId=25003",
"24x24": "https://jira.REDACTED.net/jira/secure/projectavatar?size=small&pid=16910&avatarId=25003",
"16x16": "https://jira.REDACTED.net/jira/secure/projectavatar?size=xsmall&pid=16910&avatarId=25003",
"32x32": "https://jira.REDACTED.net/jira/secure/projectavatar?size=medium&pid=16910&avatarId=25003"
},
"projectCategory": {
"self": "https://jira.REDACTED.net/jira/rest/api/2/projectCategory/10730",
"id": "10730",
"description": "",
"name": "REDACTED"
}
}
```
to me, it seems that the value used in the []jira.RequestFieldValue allow only `string` https://github.com/andygrunwald/go-jira/blob/2e11dffbdb9a4710fdc9233e8efe0a124e204e24/onpremise/request.go#L29
May changing this to empty interface or any we can allow any value to be passed
## What did you expect to happen?
A ticket to be created successfully

## How can we reproduce it (as minimally and precisely as possible)?
try to create a task in ServiceDesk

Minimal code helps us to identify the problem faster.
This depends on your jira used for testing/development. To be able to reproduce it you need field that accepts a bit more comple than a string
## Anything else we need to know?

## Your Environment

Include as many relevant details about the environment you experienced the problem in

* go-jira version (git tag or sha): main
* Go version (`go version`): go version go1.21.0 linux/amd64
* Jira type (cloud or on-premise): on-premise
* Jira version / Api version: v2