Replace github.com/pkg/errors with stdlib errors

[mversiotech]

Since Go version 1.13, the standard library has built-in support for
wrapping and unwrapping of error values. This commit bumps the minimum
version required by the module from 1.12 to 1.13, replaces all calls to
errors.Wrap/f with fmt.Errorf and removes the now unneeded dependency on
github.com/pkg/errors.

Signed-off-by: Michael Hofmann michael.hofmann@bitgestalt.com

[microsoft-cla-retired]

All CLA requirements met.

[katiewasnothere]

@bitgestalt Was there a specific need for this? I think we prefer using the errors package here.

[mversiotech]

@bitgestalt Was there a specific need for this? I think we prefer using the errors package here.

errors is a third-party package and, insofar as it is used by this module, its functionality is fully covered by the Go standard library. On top of that, errors is currently in maintenance mode and no longer actively under development and apparently also unmaintained . The one feature errors.Wrap has and fmt.Errorf has not - stack traces on errors - is only marginally useful since only a small subset of errors returned by functions in this module are created by errors.Wrap.

In short, unless you want to maintain strict compatibility with Go 1.12, I can see no good reason to keep depending on the external errors package.

[katiewasnothere]

Ah okay, seems like a bunch of projects are doing this as well. I'm fine with it then.