* modify Alamofire version in podspec
* modify Alamofire version in Package.swift
* also pin optimistically in Cartfile
* optimistically resolve all other dependencies to next major version
* [swift5] Fix additionalProps inner type
* [swift5] Add and use AnyCodable type instead of any
* [swift5] Use the original petstore w/fake models for testing default
* [swift5] Update swift-tools-version to 5.1
* [swift5] Update samples and docs