fix: missing import for url session extensions

[marandaneto]

💡 Motivation and Context

follow up #189

💚 How did you test it?

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

[dfed]

Thanks! I was about to come write this PR – latest release does not compile for me.

[github-actions]

	Fails
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## Next
- missing import for url session extensions ([#194](https://github.com/PostHog/posthog-ios/pull/194))

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