refactor: remove gotest.tools (#688)

* refactor: remove `gotest.tools`

* remove all references to `gotest.tools` and replace it with
  `github.com/stretchr/testify` which was originally used for tests
* bump `golangci-lint` version
* add `depguard` and `importas` to prevent import of unwanted packages
* add custom schema and information about config since
  schemastore.org has broken schema for `golangci-lint` config

* fix: handle more error cases

cmd/input.go

@@ -1,8 +1,9 @@
 package cmd
 
 import (
-	"log"
 	"path/filepath"
+
+	log "github.com/sirupsen/logrus"
 )
 
 // Input contains the input for the root command