Support for Stripe 6.9 release

added 9 commits

• b33ca019 - 1 commit from branch master
• 1129c8ce - Convert some internals to API4
• e87adb97 - Add Payment_details custom group and allow custom fields to be saved via Mjwpayment.create
• e5417967 - Upgrade civix
• 806cb805 - Pass through custom params in updateContributionCompleted
• 89ff6a0f - Fix keys
• 4406a23e - Minor fixes
• 8e1cf539 - Update version
• 4907ca4b - Clarify params, unset params that have a different key on the payment

Compare with previous version

added 2 commits

• 5bfa3794 - Clarify params, unset params that have a different key on the payment
• 4426c011 - Update version

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merged