Checkout specific SHA of cov-pools during installation of repositories

[michalinacienciala]

We need to checkout coverage-pools at 6a9b084, as after that commit we introduced in the the Asset Pool contract a call to a delegate function which is not present in the KeepToken contract used during AssetPool's deployment script. Using latest code from main was causing error in the E2E tests on local env., at the stage of running 05_deploy_asset_pool.ts script during installation of coverage-pools. Error was misleadingly suggesting problems with gas estimation (cannot estimate gas; transaction may fail or may require manual gas limit).

More details about the root cause:

• in PR 206 we introduced delegate function in ICollateralToken https://github.com/keep-network/coverage-pools/blob/main/contracts/interfaces/ICollateralToken.sol#L30
• in the deployment script 00_resolve_keep_token.ts KeepToken is used from the dependencies set in package.json, which does not have a delegate function https://github.com/keep-network/coverage-pools/blob/main/deploy/00_resolve_keep_token.ts#L12
• AssetPool uses KeepToken in its deployment script: https://github.com/keep-network/coverage-pools/blob/main/deploy/05_deploy_asset_pool.ts#L14
• KeepToken is passed to the Asset Pool constructor as a collateral token and tries to call a delegate function which doesn't exist https://github.com/keep-network/coverage-pools/blob/main/contracts/AssetPool.sol#L155

Workflow with E2E tests run on the feature branch: https://github.com/keep-network/local-setup/actions/runs/1817475780

Refs: https://github.com/keep-network/keep-core/pull/2818