Allow upcoming Shopify versions instead of raising UnsupportedVersionError

[netwire88]

Overview

Currently, if we are trying to test an upcoming release candidate (i.e. 2025-01, while the current version is 2024-10), we cannot. shopify_app raises this:

ShopifyAPI::Errors::UnsupportedVersionError:
  Invalid version 2025-01, supported versions: ["unstable", "2024-10", "2024-07", "2024-04", "2024-01", "2023-10", "2023-07", "2023-04", "2023-01", "2022-10", "2022-07", "2022-04", "2022-01"]

This is problematic since we cannot work on the new API version and go live at the same time since we cannot develop and test. unstable doesn't always correlated to the upcoming release candidate (2025-01 in this case), so that doesn't work.

Suggestion:
Allow upcoming release candidate API version in shopify_app

[netwire88]

Moving to Shopify/shopify-api-ruby#1353