Fix deprectated pipeline calls for Redis 4.6.0

[justinhoward]

Redis 4.6.0 deprecates accessing redis within pipeline and multi calls. Fix our calls to these methods to use the PipelinedConnection given in the block argument.

This is to pair with the rpush PR rpush/rpush#636

Since the previous versions of redis passed the Client object to the block argument, our new calling syntax is compatible with both pre-4.6.0, and post-4.6.0.

I made some decisions here that probably need some feedback from maintainers:

• Upgraded redis in the Gemfile to 4.6.0. We currently only test this single version. Should we use different versions in the CI matrix? I did write the specs to support this, mocking the correct behavior for before/after 4.6.0.
• Turned on Redis 4.6.0 deprecation errors in specs

[aried3r]

Hey! Thanks for this PR!

• Should we use different versions in the CI matrix?

Personally, I don't think so. Older versions of modis will work with older versions of redis and after this PR is merged and released, we'll support redis 4.6 without deprecation warnings.

I don't use the redis gem myself, but do they use semver? As in, will breaking changes only occur in major versions? If so, I'd say we can think about a testing matrix once 5.x is released to support 4.x and 5.x if necessary. WDYT?

• Turned on Redis 4.6.0 deprecation errors in specs

I like it! Should make maintaining a little bit easier. But we should probably then also schedule a CI run every month.

[aried3r]

But we should probably then also schedule a CI run every month.

I just saw this repo still uses Travis. I guess we should switch to GitHub actions. However I don't use modis myself and currently don't have enough time for this. I'll open an issue.

[justinhoward]

Thanks for the review and merge @aried3r!

I don't use the redis gem myself, but do they use semver? As in, will breaking changes only occur in major versions? If so, I'd say we can think about a testing matrix once 5.x is released to support 4.x and 5.x if necessary. WDYT?

Yes, redis seems to follow semver, and your suggestion makes sense to me 👍

[benlangfeld]

Switching to GH Actions in #34.