Lower deployment target and add availability checks to all Combine related code

[RonKliffer]

No description provided.

[codecov]

Codecov Report

Merging #29 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #29   +/-   ##
=======================================
  Coverage   97.41%   97.41%           
=======================================
  Files          38       38           
  Lines        2244     2244           
=======================================
  Hits         2186     2186           
  Misses         58       58           

Impacted Files	Coverage Δ
Sources/Common/DemandBuffer.swift	100.00% <ø> (ø)
Sources/Common/Sink.swift	57.50% <ø> (ø)
Sources/Models/Event.swift	52.63% <ø> (ø)
Sources/Operators/Amb.swift	100.00% <ø> (ø)
Sources/Operators/AssignToMany.swift	100.00% <ø> (ø)
Sources/Operators/CombineLatestMany.swift	100.00% <ø> (ø)
Sources/Operators/Create.swift	100.00% <ø> (ø)
Sources/Operators/Dematerialize.swift	85.18% <ø> (ø)
Sources/Operators/FlatMapLatest.swift	100.00% <ø> (ø)
Sources/Operators/MapMany.swift	100.00% <ø> (ø)
... and 28 more

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[freak4pc]

Me and @RonKliffer had a discussion around this yesterday, after I've heard this use-case from several people.

There are people who actually use Combine in newer portions of their apps, e.g. iOS 11 apps that want to use this dependency with an availability clause. I think it's a valid use-case overall. WDYT @jasdev @jdisho ?

[freak4pc]

All tests should stay iOS 13 and up. Only the target itself should be iOS 11+
I'm actually not sure it's possible, but worth checking

[jdisho]

Seems valid case to me too.👌

[jdisho]

Should we do the same thing for SPM?

[jasdev]

WDYT @jasdev @jdisho?

Cool with me—no concerns on my end as long as you also think this is the right call for 11.x+ folks. 👌🏽

[freak4pc]

Thank you @RonKliffer ! Ran everything locally and this looks good 💯