[tx-generator] Enable windows build

[palas]

Description

This PR enables windows build for tx-generator and ensures it builds in the CI. This is necessary because we'll need to depend on it in cardano-testnet, and the later already builds for windows.

Related PRs

• [cardano-testnet] Apply stylish-haskell
• [tx-generator] Enable windows build <- this PR
• [cardano-testnet] - Add flag to generate a template configuration for tx-generator

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Runnings tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-9.6 and ghc-9.12
• Self-reviewed the diff

[erikd]

LGTM!