Fix scan issue when encountering invalid symlinks (#871)

* Implement fixed symwalk algorithm
* Remove dependency

pkg/manager/task_scan.go

@@ -11,7 +11,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/facebookgo/symwalk"
 	"github.com/jmoiron/sqlx"
 
 	"github.com/stashapp/stash/pkg/database"
@@ -655,7 +654,7 @@ func walkFilesToScan(s *models.StashConfig, f filepath.WalkFunc) error {
 	excludeVid := config.GetExcludes()
 	excludeImg := config.GetImageExcludes()
 
-	return symwalk.Walk(s.Path, func(path string, info os.FileInfo, err error) error {
+	return utils.SymWalk(s.Path, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			logger.Warnf("error scanning %s: %s", path, err.Error())
 			return nil