Add support for .yml file extension in config file

Signed-off-by: Onni Hakala <onni@flaky.build>

Author: onnimonni

config/config.go

@@ -39,17 +39,20 @@ var fs fileSystem = osFS{stat: os.Stat}
 const (
 	maxDepth       = 100
 	configFileName = ".sops.yaml"
+	configFileNameAlternative = ".sops.yml"
 )
 
 // FindConfigFile looks for a sops config file in the current working directory and on parent directories, up to the limit defined by the maxDepth constant.
 func FindConfigFile(start string) (string, error) {
 	filepath := path.Dir(start)
 	for i := 0; i < maxDepth; i++ {
-		_, err := fs.Stat(path.Join(filepath, configFileName))
-		if err != nil {
-			filepath = path.Join(filepath, "..")
-		} else {
-			return path.Join(filepath, configFileName), nil
+		for _, configFileName := range []string{configFileName, configFileNameAlternative} {
+			_, err := fs.Stat(path.Join(filepath, configFileName))
+			if err != nil {
+				filepath = path.Join(filepath, "..")
+			} else {
+				return path.Join(filepath, configFileName), nil
+			}
 		}
 	}
 	return "", fmt.Errorf("Config file not found")