helm dependency upgrade wasn't working on certain file system because it assumes that os.rename is available. Since rename isn't available for subfolders in docker containers, I ripped a fallback rename strategy from dep (https://github.com/golang/dep/blob/5b1fe9e6d89372487d0aac78d9c5362a517857e7/internal/fs/fs.go#L103-L118

) that works in docker.

Signed-off-by: Brice Rising <brice.rising@slalom.com>
(cherry picked from commit 94d87ef9)