Invalid external-name on repository rulesets

The resouerce tries to observe to calculate mutations, however because the `external-name` is wrong it can never import the resource and it thus fails.

The upstream terraform confirms this suspicion that it should not be the name string but rather the ID.

```
[Attributes Reference](https://registry.terraform.io/providers/integrations/github/latest/docs/resources/repository_ruleset#attributes-reference)
The following additional attributes are exported:

[etag](https://registry.terraform.io/providers/integrations/github/latest/docs/resources/repository_ruleset#etag-1) (String)

[node_id](https://registry.terraform.io/providers/integrations/github/latest/docs/resources/repository_ruleset#node_id-1) (String) GraphQL global node id for use with v4 API.

[ruleset_id](https://registry.terraform.io/providers/integrations/github/latest/docs/resources/repository_ruleset#ruleset_id-1) (Number) GitHub ID for the ruleset.
```

Error:

```log
"message": "observe failed: failed to observe the resource: [{0 Unexpected ID format (\"REDACTED\"), expected numerical ID. strconv.ParseInt: parsing \"REDACTED\": invalid syntax []}]",
```