[FEATURE]: Support for `enable_beta_languages`

[mnatsakanovsuren]

Hi there 👋

I'm using strapi-plugin-translate with the DeepL provider and noticed that the enable_beta_languages option from the DeepL API is not currently supported in strapi-provider-translate-deepl.

I tried adding the following to my plugin config:

providerOptions: {
  apiKey: 'my-key',
  apiUrl: 'https://api-free.deepl.com',
  apiOptions: {
    enable_beta_languages: true,
  },
}

However, it seems this parameter is not passed to the DeepL client internally. As a result, beta languages like Hindi are not accessible, and translation attempts fail with errors like:

Code
Translation of entity from en to hi failed

Feature request
Could you please add support for forwarding apiOptions (or at least enable_beta_languages) to the DeepL client when initializing the provider? This would allow users to access beta languages and other advanced DeepL features.

[Pfenya]

I was coming here to request the same - Croatian is also currently in beta and we would like to be able to use that.

[Pfenya]

I had a look and it seems to be a two line change as far as I can tell so I took the liberty of opening a pull request with the needed changes: #536