GitHub env file support (#426)

* Upgrade to the official golangci-lint action and fix some issues it found

* Update deps

* Remove a shadow warning

* Initialize the splitPattern only once

* Initial attempt at supporting $GITHUB_ENV

Needs some polishing and tests

* Now it's actually working

* Replace golang.org/x/crypto/ssh/terminal with golang.org/x/term

* Disable the issue-228 test again

* The linter is picky

* Discovered that the workflow/envs.txt had to exist in certain cases

* Fix small linter issue

pkg/common/git.go

@@ -157,7 +157,6 @@ func findGitDirectory(fromFile string) (string, error) {
 		return "", err
 	}
 
-	//log.Debugf("Searching for git directory in %s", absPath)
 	fi, err := os.Stat(absPath)
 	if err != nil {
 		return "", err