Fix gofmt_check makefile target.

[andrewsomething]

Happened to notice that our gofmt_check makefile target is not running correctly in CI:

https://github.com/digitalocean/doctl/runs/1751541753?check_suite_focus=true#step:5:8

Output before change:

asb@asb-home:~/development/gocode/src/github.com/digitalocean/doctl$ make gofmt_check
==> ensure code adheres to gofmt (with vendor directory excluded)

/bin/sh: 1: read: arg count
asb@asb-home:~/development/gocode/src/github.com/digitalocean/doctl$ echo $?
0

Output after change:

asb@asb-home:~/development/gocode/src/github.com/digitalocean/doctl$ make gofmt_check
==> ensure code adheres to gofmt (with vendor directory excluded)

gofmt checking failed:

./commands/validations.go 

make: *** [Makefile:112: gofmt_check] Error 1
asb@asb-home:~/development/gocode/src/github.com/digitalocean/doctl$ echo $?
2

[ChiefMateStarbuck]

sweet!