Address golangci-lint deprecation warnings, enable some more linters (#2152)

* Address golangci-lint linter deprecation warnings

1.59.0 outputs:

WARN [lintersdb] The name "gas" is deprecated. The linter has been renamed to: gosec.
WARN [lintersdb] The linter named "megacheck" is deprecated. It has been split into: gosimple, staticcheck, unused.

* Enable some more linters, address finding