Use gosec error checking exclusively

This MR turns off the errcheck linter in favor of gosec.

It is not possible to only disable the error checking of gosec and it reports other useful errors.

Additionally, errcheck reports unchecked errors on defer response.Body.Close(), which is generally unhelpful.

This MR should prevent some of the -n/+n code quality issues in MRs that come up in code climate which is by linters contending for the same file and line number.