[Justin Hammond (Justintime50)]

Description

Preps v8.9.0 for release: bumps the version and dates the CHANGELOG entry.

• Adds surcharges to Rate and a Surcharge model
• Removes the deprecated, unusable addCreditCard function
  • Stripe has disabled the ability to pass plain credit card details over the wire and now requires using Stripe.js/Elements/Checkout. Follow the Decentralized (EasyPost-Manage Billing) Guide for more details on the new flow to use.
  • Makes referralCustomer.retrieveEasypostStripeApiKey public to help facilitate adding credit cards using Stripe.js
• Adds support for FedexDefaultAccount, GofoWalletAccount, UpsDapAccount, UniUniWalletAccount, and VehoWalletAccount by properly routing carrier-account create requests to the /carrier_accounts/open endpoint
• Also pins CI runners from ubuntu-latest to ubuntu-24.04: ubuntu-latest moved to Ubuntu 26.04, which dropped older language versions from our test matrix, so this keeps CI on 24.04 until a later modernization effort.
• Also drops roave/security-advisories in CI on the PHP 8.1 job only (composer remove --dev --no-update before install): its latest advisories conflict with every PHP 8.1 release (8.1 is EOL), so composer install could not resolve. composer.json and PHP 8.2+ jobs are unchanged.

Testing

Pull Request Type

Please select the option(s) that are relevant to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)

Reviewer notes

• The removal of the deprecated, unusable credit-card function ships as a minor release, following the easypost-go v5.10.0 precedent (which removed AddReferralCustomerCreditCard in a minor).