ci/cd: run simple go fmt on ci stage

[Kamil Samigullin]

Motivation: pre-push can handle unformatted code, but it doesn't start at the checking stage, because there are no goimports and other tools.

For example

• works well https://github.com/octomation/maintainer/actions/runs/2436302897
• but octomation/maintainer@fc48373 doesn't contain

diff --git a/internal/command/github/view/diff.go b/internal/command/github/view/diff.go
index 8c19d61..b584cae 100644
--- a/internal/command/github/view/diff.go
+++ b/internal/command/github/view/diff.go
@@ -2,6 +2,7 @@ package view
 
 import (
        "fmt"
+
        "github.com/alexeyco/simpletable"