Final params for BqETHSubscription deployment on mainnet

[cygnusv]

Type of PR:

• [ ] Bugfix
• [ ] Feature
• [ ] Documentation
• [ ] Other

Required reviews:

• [ ] 1
• [ ] 2
• [X] 3

What this does:

High-level idea of the changes introduced in this PR. List relevant API changes (if any), as well as related PRs and issues.

Issues fixed/closed:

• Fixes #...

Why it's needed:

Explain how this PR fits in the greater context of the NuCypher Network. E.g., if this PR address a nucypher/productdev issue, let reviewers know!

Notes for reviewers:

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[cygnusv]

This is currently deployed on Mainnet

[derekpierre]

This is currently deployed on Mainnet

Separate from this PR:

1. We've been using testnet tags for tracking the code currently deployed on the various testnets:
   • https://github.com/nucypher/nucypher-contracts/tree/lynx
   • https://github.com/nucypher/nucypher-contracts/tree/tapir
   • https://github.com/nucypher/nucypher-contracts/tree/mainnet

Not sure if we updated lynx and mainnet tags, but those should be updated accordingly.

2. It's likely that tapir contracts are now older than mainnet, so tapir should be updated.