error with dependency `haskell-src-exts == 1.20.*`

[peterbecich]

Using GHC 8.6.5, if I change the bound here

haskell-src-meta/haskell-src-meta/haskell-src-meta.cabal

Line 22 in f5bf8e4

haskell-src-exts >= 1.18 && < 1.24,

to haskell-src-exts == 1.20.*, this error occurs:

[2 of 5] Compiling Language.Haskell.Meta.Syntax.Translate ( src/Language/Haskell/Meta/Syntax/Translate.hs, .../haskell-src-meta/dist-newstyle/build/x86_64-linux/ghc-8.6.5/haskell-src-meta-0.8.8/build/Language/Haskell/Meta/Syntax/Translate.o ) [Language.Haskell.Exts.Syntax changed]

src/Language/Haskell/Meta/Syntax/Translate.hs:493:19: error:
    Not in scope: data constructor ‘Exts.DerivVia’
    Perhaps you meant ‘Exts.Deriving’ (imported from Language.Haskell.Exts.Syntax)
    Module ‘Language.Haskell.Exts.Syntax’ does not export ‘DerivVia’.
    |
493 | toDerivStrategy d@Exts.DerivVia{}      = noTHyet "toDerivStrategy" "2.14" d
    |                   ^^^^^^^^^^^^^
cabal: Failed to build haskell-src-meta-0.8.8 (which is required by test:unit
from haskell-src-meta-0.8.8, test:splices from haskell-src-meta-0.8.8 and
others).

GHC 8.6.5 is used by CodeWorld: google/codeworld#1566 (comment)

Thanks