v2.9.0

@nikololiahim

Cats v2.9.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.2+ with Scala.js 1.8+ and Scala Native 0.4.

What's Changed

Added updated to Traverse by @nikololiahim in #4248
Added zipWithLongIndex, mapWithLongIndex and traverseWithLongIndexM by @nikololiahim in #4247
Add collectFirst to the NonEmptyCollection interface by @DavidGregory084 in #4275
Added discipline tests for the new Traverse laws by @nikololiahim in #4283
Add traverseCollect to TraverseFilter typeclass by @emilhotkowski in #4277
Add NonEmptyList#prependAll by @saeltz in #4267
Add EitherT#biSemiflatTap which combines leftSemiflatTap and semiflatTap by @exp0nge in #4293
Optimize Alternative (part 3): add prependK/appendK specializations for Cats NE wrappers by @satorg in #4055
Added parFlatMapN by @TonioGela in #4243
Added Align instances for Id and Kleisli by @atnoya in #4287
Add ApplicativeError#voidError by @armanbilge in #4324

Change the ordering of invocations in Defer#fix by @TimWSpence in #4252
Optimise boilerplate generators, use instance constructors by @joroKr21 in #3871
Avoid using NonFatal.unapply by @jhnsmth in #4282
Use SAM syntax for typeclass instances where possible by @joroKr21 in #4279
Singleton monoid instances by @TimWSpence in #4314
Avoid allocations for Monoid instances where possible by @bplommer in #4309
Make string building a bit more efficient for NonEmptySeq by @danicheg in #4326

Don't require Order for the value on Cogen for SortedMap and NonEmptyMap by @cquiroz in #4296
Make cats.compat a package object for for2_13Use3 compatibility by @TonioGela in #4315
Fix ambiguous contains_ syntax by @armanbilge in #4320

Remove LEGO from adopters list by @hejfelix in #4242
Fix Free Monad example by @youta32449999 in #4253
Mention asRight and asLeft for constructing Either values by @benhutchison in #4257
Fix comment in Free Monad example by @youta32449999 in #4259
Add proof of inconsistency for a Validated Monad by @TonioGela in #4255
Mention tupled syntax, a Cats workhorse that deserves to be more well known by @benhutchison in #4269
Add missing scala modifier to code block by @armanbilge in #4274
Build docs on 2.13 by @armanbilge in #4238
Fix list formatting in docs / site by @valencik in #4290
Move the adopters' companies list to a separate file/page by @danicheg in #4291
Keep the cats version up to date on the website by @danicheg in #4294
Include laws in published API docs by @armanbilge in #4318
Fix markdown syntax for link to Applicative in OptionT by @yoshinorin in #4321
Add more DocTests for OptionT by @timo-schmid in #4311

Update sbt-scalajs, scalajs-compiler, ... to 1.10.1 by @typelevel-steward in #4254
Update nscplugin, sbt-scala-native, ... to 0.4.7 by @typelevel-steward in #4289
Update scalacheck to 1.17.0 by @typelevel-steward in #4297
Update scala3-library, ... to 3.2.1 by @typelevel-steward in #4337

Full Changelog: v2.8.0...v2.9.0