Update contract licenses to MIT

[jacque006]

What is this PR doing?

• Update SPDX-License-Identifier contract license metadata from Unlicense to MIT for consistency with rest of repo.
• No other non-MIT license references were discovered

How can these changes be manually tested?

👀 , 🧑‍⚖️

Does this PR resolve or contribute to any issues?

Resolves #607

Checklist

I have manually tested these changes No testing needed

• Post a link to the PR in the group chat

Guidelines

• If your PR is not ready, mark it as a draft
• The resolve conversation button is for reviewers, not authors
  • (But add a 'done' comment or similar)

[jacque006]

Updating the SPDX-License-Identifier appears to have changed the contract bytecode. This will have conflicts with #606 depending on which goes in first (deps.ts, package.jsons, etc.)

[JohnGuilding]

Looks good.

Only question is, should contracts/clients/package.json version be updated to 0.9.0-5d98448?

[jacque006]

@JohnGuilding That clients version was pinned to an experimental release in main when I started this work. It doesn't seem to be causing any harm so I rolled with it.

When we pin v1, we can set it back to a non-experimental semver. Set it back in this PR