Update fog-google to v1.25.0 and excon to v1.3.0

What does this MR do and why?

This update to fog-google finally unblocks updates to excon and fog-core so that fog-aws can be updated.

Diffs:

• fog-google: https://my.diffend.io/gems/fog-google/1.24.1/1.25.0
• fog-core: https://my.diffend.io/gems/fog-core/2.1.0/2.6.0
• excon: https://my.diffend.io/gems/excon/0.99.0/1.3.0

How to set up and validate locally

1. Set up your GDK with Google object storage: https://gitlab-org.gitlab.io/gitlab-development-kit/howto/object_storage/#google-cloud-storage
2. gdk restart rails
3. Attempt to attach images and upload CI artifacts.

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.