[REQ] OpenISO8601DateFormatter date without zone

Is your feature request related to a problem? Please describe.

OpenISO8601DateFormatter supports a full ISO8601 format, date without time and without milliseconds. In case of responses that are not specifying Z, the formatter fails with an error Date string does not match format expected by formatter.

Describe the solution you'd like

Add an additional fallback with next method

static let withoutZone: DateFormatter = {
        let formatter = DateFormatter()
        formatter.calendar = Calendar(identifier: .iso8601)
        formatter.locale = Locale(identifier: "en_US_POSIX")
        formatter.timeZone = TimeZone(secondsFromGMT: 0)
        formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
        return formatter
 }()

then override override public func date(from string: String) -> Date? method with

override public func date(from string: String) -> Date? {
        if let result = super.date(from: string) {
            return result
        } else if let result = OpenISO8601DateFormatter.withoutSeconds.date(from: string) {
            return result
        } else if let result = OpenISO8601DateFormatter.withoutZone.date(from: string) {
            return result
        }

        return OpenISO8601DateFormatter.withoutTime.date(from: string)
}

Start by locating OpenISO8601DateFormatter and its date(from:) implementation in the Swift client code. Compare the existing formatter fallbacks with the requested withoutZone format, then verify that ISO 8601 date-time strings without a zone are accepted without breaking the existing formats.