Update Server and Direct gateways to support protocol version 4.0

[nfourtythree]

This pull request provides an update to the protocol version for the impending 14th March deadline imposed by Opayo/SagePay. The PR is only related to the change in protocol and does not add any other integrations.

Both the Direct and Server gateways are updated to work with the new protocol.

Points of note

• ~Reverted PHP version requirement back to 7.2 as our Craft CMS product has 7.2.5 as the lowest version required.~ Left the version as ^7.3 due to dependency requirements.
• Hardcoded the change to the protocol version to 4.00, this means there is a need for the next release (when merged) to be a major version to avoid breaking anyone's projects.

Merging this will help us release a new version of our SagePay plugin to meet the upcoming requirement changes being enforced by Opayo.

This will also resolve the craftcms/commerce-sagepay#20 issue that we have outstanding, in which we will create a new release for people to update to after this package has been updated.

Let me know your feedback and thoughts, thanks!

[barryvdh]

Thanks, can you look into the tests?

[nfourtythree]

Just to note I have also reverted the PHP change. There are too many dependencies issues to go back down to ^7.2 so have bumped it back to ^7.3

[barryvdh]

Branch alias is bumped to 4.0 so you can test with ^4@dev

[jamieburchell]

@nfourtythree @barryvdh What happens when this is introduced in to a project where there are pending protocol v3 transactions? Will the signature checks fail/mismatch, or is it OK because the new fields will be empty strings and not affect the signature?

[barryvdh]

No clue

[steveWinter]

No clue

Apparently neither had I (hence why I deleted the comment) - I'd been trying to update league/omnipay and not omnipay/sagepay 🤦

[barryvdh]

Yeah no I saw your mistake there but your comment was gone 😅

No clue was about the switch between V3 and V4 mid transaction

[jamieburchell]

I tried it - registered the transaction with old protocol 3 code, upgraded to protocol 4 code, completed transaction. It worked and showed protocol version 4 in the notification data. I was expecting it to say 3, since the documentation says it's whatever was supplied originally, but whatever.

[terryupton]

I left a note on the Craft Commerce thread https://github.com/craftcms/commerce-sagepay/issues/20

We have tested this on both a standard install and a slightly custom install with some additional functionality around tokens and both sites are working fine and transactions are working as expected.