Update version of deprecation to 1.0.0-RC2

[rossabaker]

This updates the deprecations we previously expected to debut in 1.0.0.

[rossabaker]

Discussion of a potential RC2. If that happens, we should get this in. If that doesn't, we should Close Without Merge™.

[kailuowang]

Thanks!

[codecov-io]

Codecov Report

Merging #2108 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2108   +/-   ##
=======================================
  Coverage   94.79%   94.79%           
=======================================
  Files         325      325           
  Lines        5494     5494           
  Branches      219      219           
=======================================
  Hits         5208     5208           
  Misses        286      286

Impacted Files	Coverage Δ
core/src/main/scala/cats/data/WriterT.scala	93.13% <ø> (ø)	⬆️
core/src/main/scala/cats/data/IndexedStateT.scala	89.36% <ø> (ø)	⬆️
core/src/main/scala/cats/data/Kleisli.scala	97.89% <ø> (ø)	⬆️
...in/scala/cats/data/IndexedReaderWriterStateT.scala	99.06% <ø> (ø)	⬆️
free/src/main/scala/cats/free/Coyoneda.scala	84.61% <ø> (ø)	⬆️

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[LukaJCB]

Thanks for this!