fix: Resolve version before checking arch

[abhinav]

Fixes a bug where gimme module reports the following error
on macOS with ARM64.

error: arm64 is not supported by this go version
try go1.5 or newer

This occurs because the check for architecture
is performed before the module version
turns into a real version number with _resolve_version.

Fix by resolving version number before checking the architecture.

[brackendawson]

This fix works for me from 1.16 (when darwin/arm64 support was added). But the behaviour if the go directive specifies <1.16 changes from a partially incorrect error message (should say 1.16 on darwin):

% gimme module
error: arm64 is not supported by this go version
try go1.5 or newer

to an unhelpful error message:

% gimme module
I don't have any idea what to do with '1.13.15'.
  (using download type 'auto')

Can we restore the original error message but correct the version number for darwin? 1.5 was when linux/arm64 support was added.

[brackendawson]

Also this needs to change, perhaps:

To install the release specified in the go.mod file, or the most recent patch when no patch version is present:

[abhinav]

Sounds good!
Updated the arm64 version matching.

Agreed about the README change too.
Should've done that in #25, but late is better than never.
Updated to reflect new behavior.

[brackendawson]

New error message looks good but it still doesn't actually show up:

% uname -sm
Darwin arm64
% cat go.mod
module github.com/urfave/gimme/test

go 1.13
% ../gimme module
I don't have any idea what to do with '1.13.15'.
  (using download type 'auto')

[abhinav]

That's weird.

❯ uname -sm
Darwin arm64

❯ head -n3 go.mod
module github.com/urfave/gimme

go 1.13

❯ ./gimme module
error: arm64 is not supported by this go version
try go1.16 or newer

[brackendawson]

My bad, it works better when you pull all the changes in the branch. Thank you.