ios prebid sdk version : 2.4.0 : Crash on bid.ext.prebid.meta getter in Bid.swift

[jangirtony2009]

Describe the bug
If the bid-meta from the server is not of type [String: String], it will cause a crash. As per ORTB and Prebid norms, bid-meta can be a JSON model type.

prebid-mobile-ios/PrebidMobile/PrebidMobileRendering/Prebid/PBMCore/Bid.swift

Line 67 in 9947afd

public var meta: [String : String]? {

To Reproduce
Steps to reproduce the behavior:

1. Request for an ad.
2. If in the response bid.ext.prebid.meta is not [String: String] type of response.
3. and render tries to access the meta info

Expected behavior
It should not cause a crash.

Screenshots
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Desktop (please complete the following information):

• OS: ios
• Browser [e.g. chrome, safari]
• SDK Version 2.4.0

Smartphone (please complete the following information):

• Device: all
• OS: all
• Browser all
• Version all

Additional context
Add any other context about the problem here.