test against version 7.4-rc1 issue #2738

[atakavci]

Closes/Fixes #2738

this is just to move the integration test against to newer version of Redis

[uglide]

@mgravell @NickCraver

Could you review and merge this change so we can actually test 7.4 related PRs in CI?

Pending 7.4 PRs: https://github.com/StackExchange/StackExchange.Redis/pull/2716 https://github.com/StackExchange/StackExchange.Redis/pull/2722 https://github.com/StackExchange/StackExchange.Redis/pull/2727