minor fix for deprecated podspec.
minor fix for deprecated podspec.

VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-ios