Widen template-haskell version constraint to allow version <2.22

This allows freer-simple to be used with GHC >= 9.4. Prior versions of
template-haskell are not compatible with those GHC versions. Newer
version of of template-haskell seem to be fully compatible with
freer-simple. That is, tests still pass and I haven't noticed any
issues in my own project (which use freer-simple).

Fixes #40

freer-simple.cabal

@@ -84,7 +84,7 @@ library
  build-depends:
  , natural-transformation >= 0.2
  , transformers-base
- , template-haskell >= 2.11 && < 2.19
+ , template-haskell >= 2.11 && < 2.22
 
 executable freer-simple-examples
  import: common