[#134] Add CHAIN_ID to multisigs

Description

Problem: Reference implementation for multisig contract was recently updated with CHAIN_ID instruction, which guarantees additional security.

Solution: Update our multisigs as well.

Related issue(s)

Resolves #134 (closed)

✅ Checklist for your Merge Request

Related changes (conditional)

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

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  • I checked whether I should update the docs and did so if necessary:
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    • Haddock
    • docs/
  • I updated changelog files of all affected packages released to Hackage if my changes are externally visible.

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