Upstep Go dependencies (#340)

* Upstep Go dependencies

* tiny linter fix

* Tidy

vendor/github.com/spf13/viper/fs.go

@@ -0,0 +1,65 @@
+//go:build go1.16 && finder
+// +build go1.16,finder
+
+package viper
+
+import (
+	"errors"
+	"io/fs"
+	"path"
+)
+
+type finder struct {
+	paths      []string
+	fileNames  []string
+	extensions []string
+
+	withoutExtension bool
+}
+
+func (f finder) Find(fsys fs.FS) (string, error) {
+	for _, searchPath := range f.paths {
+		for _, fileName := range f.fileNames {
+			for _, extension := range f.extensions {
+				filePath := path.Join(searchPath, fileName+"."+extension)
+
+				ok, err := fileExists(fsys, filePath)
+				if err != nil {
+					return "", err
+				}
+
+				if ok {
+					return filePath, nil
+				}
+			}
+
+			if f.withoutExtension {
+				filePath := path.Join(searchPath, fileName)
+
+				ok, err := fileExists(fsys, filePath)
+				if err != nil {
+					return "", err
+				}
+
+				if ok {
+					return filePath, nil
+				}
+			}
+		}
+	}
+
+	return "", nil
+}
+
+func fileExists(fsys fs.FS, filePath string) (bool, error) {
+	fileInfo, err := fs.Stat(fsys, filePath)
+	if err == nil {
+		return !fileInfo.IsDir(), nil
+	}
+
+	if errors.Is(err, fs.ErrNotExist) {
+		return false, nil
+	}
+
+	return false, err
+}