Add duckduckgo-search to slim requirements,

[hlohaus]

Add pass provider as model in the client,
Fix missing @Property in version utils

[github-actions]

Review by G4F Copilot

Thank you, H Lohaus, for your contribution to the project. Here is the review of your pull request:

1. Changes Made:

   • Added duckduckgo-search to slim requirements.
   • Added pass provider as a model in the client.
   • Fixed missing @property in version utils.

2. Code Changes:

   • Updated async_client.md to use g4f.Provider.CopilotAccount as the provider.
   • Updated information in legacy.md about providers.
   • Added tests for model not found, best provider, provider as a model, and get model.
   • Updated code in various files related to Copilot provider.
   • Updated code in client.py to handle exceptions when model or provider is not found.
   • Updated CSS and JavaScript files for version information.

3. Overall Feedback:

   • The changes look good and align with the requirements.
   • The addition of duckduckgo-search to the requirements is a useful update.
   • The test cases provide good coverage for the added functionality.
   • The code changes are clear and follow good coding practices.

Thank you for your contribution, and please address any feedback provided before merging the pull request.