Update test to avoid Azure content filter

[marklysze]

Why are these changes needed?

The text in the sample data feed in test_async.py is triggering the Azure OpenAI content filter. This updates the text to avoid that as it's not the purpose of this test.

{ "title": "Palantir CEO Says Our Generation's Atomic Bomb Could Be AI Weapon - And Arrive Sooner Than You Think - Palantir Technologies ( NYSE:PLTR ) ", "summary": "Christopher Nolan's blockbuster movie \"Oppenheimer\" has reignited the public discourse surrounding the United States' use of an atomic bomb on Japan at the end of World War II.", "overall_sentiment_score": 0.009687, },
to
{ "title": "Palantir CEO Says Our Generation's Main Challenge Could Be AI Against Humanity - And Arrive Sooner Than You Think - Palantir Technologies ( NYSE:PLTR ) ", "summary": "Christopher Nolan's blockbuster movie \"Oppenheimer\" has reignited the public discourse surrounding the United States' use of a weapon on Japan at the end of World War II.", "overall_sentiment_score": 0.009687, },

Also updated the model used from gpt-3.5-turbo to gpt-4o-mini.

Related issue number

N/A

Checks

• I've included any doc changes needed for https://ag2ai.github.io/ag2/. See https://ag2ai.github.io/ag2/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[qingyun-wu]

LGTM! Thanks!