Feat: Singleton deployments supported

[cbrzn]

Changes suggested on this PR:

• Hardhat version updated, making matic deployments work
• Updated solidity coverage to support london fork
• Node version upgraded to 16 to make it compatible with latest hardhat version

[github-actions[bot]]

CLA Assistant Lite All Contributors have signed the CLA.

[coveralls]

Pull Request Test Coverage Report for Build 1234895438

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 1225530621:	0.0%
Covered Lines:	96
Relevant Lines:	96

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💛 - Coveralls