Ignore Info.plist in the Swift Package

[csykes]

What does this PR do?

• Avoids generating a warning in a client's project when including the posthog-ios package

Where should the reviewer start?

• Setup another Xcode project that uses the posthog-ios package and verify you don't see the warning about the Info.plist file

How should this be manually tested?

Any background context you want to provide?

What are the relevant tickets?

Screenshots or screencasts (if UI/UX change)

Questions:

• Does the docs need an update?
• Are there any security concerns?
• Do we need to update engineering / success?

[mariusandra]

Thanks as well! Released as 1.4.2

[csykes]

Nice! And now my package update looks like this... makes me smile