Update to use SecKeyCreateRandomKey

[LowAmmo]

iOS 15.0 deprecated SecKeyGeneratePair, so would appreciate updating to SecKeyCreateRandomKey to eliminate a warning.

Pretty easy to change over -

    var privateKey: SecKey?
    var publicKey: SecKey?

    do {
        var error: Unmanaged<CFError>?

        // The keys are automatically stored in the keychain
        guard let privKey = SecKeyCreateRandomKey(attributes as CFDictionary, &error) else {
            throw error!.takeRetainedValue() as Error
        }
        privateKey = privKey
        publicKey = SecKeyCopyPublicKey(privateKey!)
    } catch {
        ulog.error(error: error, "Error creating public/private keys")
    }

[dannys42]

@LowAmmo Thanks! Please submit a PR

[LowAmmo]

@dannys42 - Sure, I'll work on putting one together!

[LowAmmo]

@dannys42 - Created pull request (above)

As a note...wasn't sure about versioning. Went ahead and upped the version of the podspec in the PR...but not sure if that was the right way to do it...