Linter: Update to new customer linter API

golangci-lint v1.54 updates[0] the contract custom linters should use
from an `AnalyzerPlugin` interface to a
`New(any) ([]*analysis.Analyzer, error)` function. A deprecation warning
for the old API is occurring when executing `make lint`.

Update to the new API to silence the warning.

[0] https://github.com/golangci/golangci-lint/pull/3887