feat: Update gtk2hs-buildtools version to fix `stack build` in some cases

[OlaoluwaM]

As noted here: https://github.com/haskell/ThreadScope/issues/122

[Mikolaj]

@OlaoluwaM: thank you for the PR. Do you need help with CI? Maybe running haskell-ci regenerate would help? I think you could commit the result in a separate commit in the same PR.