ParseInstallation not being saved in Keychain

New Issue Checklist

[x] I am not disclosing a vulnerability.
[x] I am not just asking a question.
[x] I have searched through existing issues.
[x] I can reproduce the issue with the latest versions of Parse Server and the Parse Swift SDK.

Issue Description

ParseInstallation.current found not nil only after a fresh install (cleared keychain) and on further app runs found always nil.

Steps to reproduce

0) clear simulator or device keychain 1) run ParseSwift initialisation in didFinishLaunchingWithOptions and print ParseInstallation.current

   func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        ParseSwift.initialize(applicationId: "...",
                              clientKey: "...",
                              serverURL: URL(string: "https://parseapi.back4app.com")!,
                              liveQueryServerURL: URL(string: "https://felse.b4a.io")!,
                              allowCustomObjectId: true)
        print("installation is nil: \(Installation.current == nil)")
        return true
    }

2) restart app without any activity and observe the ParseInstallation.current being nil on second and further launch

Actual Outcome

A currentInstallationContainer: CurrentInstallationContainer<Self> is retrieved from Keychain with set properly installationId but with nil currentInstallation

CurrentInstallationContainer(currentInstallation: nil, installationId: Optional("f4ec6107-8d0b-4718-801b-33e97c64c3ea"))

Expected Outcome

currentInstallation should have been saved during the first run

Environment

Client

Parse Swift SDK version: 1.9.9
Xcode version: 12.5
Operating system (iOS, macOS, watchOS, etc.): iOS
Operating system version: 14.5.

Server

Parse Server version: 4.5.0
Operating system: unknown (back4app service provider)
Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): unknown (back4app service provider)

Database

System (MongoDB or Postgres): unknown (back4app service provider)
Database version: `unknown (back4app service provider)
Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): unknown (back4app service provider)

Logs

Further description of the issue discussed in issue 171

parse-community / Parse-Swift