Re-enable checkers and move it to my packages

Fixes #5433.

build-constraints.yaml

@@ -474,6 +474,7 @@ packages:
         - bsb-http-chunked
         - coercible-utils < 0 # ghc 8.10
         - hspec-parsec
+        - checkers
 
     "Joe M <joe9mail@gmail.com> @joe9":
         - logger-thread < 0 # via protolude
@@ -965,7 +966,7 @@ packages:
     "Mario Blazevic <blamario@yahoo.com> @blamario":
         - monad-parallel
         - monad-coroutine
-        - incremental-parser < 0 # via checkers
+        - incremental-parser
         - monoid-subclasses
         - picoparsec < 0 # BuildFailureException Process exited with ExitFailure 1: ./Setup build
         - rank2classes
@@ -1484,7 +1485,7 @@ packages:
         - ghcjs-perch < 0 # build failure with GHC 8.4
 
     "Tom Ellis <tom-stackage@jaguarpaw.co.uk> @tomjaguarpaw":
-        - opaleye < 0 # via checkers
+        - opaleye
         - product-profunctors
 
     "Samplecount stefan@samplecount.com @kaoskorobase":
@@ -1671,7 +1672,7 @@ packages:
         - getopt-generics
         - graph-wrapper
         - string-conversions
-        - hspec-checkers < 0 # via checkers
+        - hspec-checkers
         - FindBin
 
     "Jan Stolarek <jan.stolarek@p.lodz.pl> @jstolarek":
@@ -4345,7 +4346,6 @@ packages:
         - cereal
         - cereal-text
         - cereal-vector
-        - checkers < 0 # https://github.com/commercialhaskell/stackage/issues/5433
         - chunked-data
         - cipher-aes128 < 0 # via Cabal-3.0.0.0
         - cipher-blowfish < 0 # MonadFail
@@ -4526,7 +4526,7 @@ packages:
         - monads-tf
         - mono-traversable-instances
         - mono-traversable-keys
-        - multiset < 0 # via checkers
+        - multiset
         - mwc-random
         - names-th
         - nanospec