go modules update

make client more resilient with servers that don't support full protocol

Bugfix and small feature release.

First release in some time. Fixing lots of bugs and adds a few new
features. Below are the highlights.

Features:
* [GH-301] support rename extension for server
* [GH-332] Added a ClientOption to determine whether to use Fstat or Stat
* [GH-315] make SFTP extensions configurable

Bugfixes:
* [GH-291] Wrong S_IFMT mask when converting filemode bits to os.FileMode
* [GH-295] sftp resume produces corrupted files
* [GH-298] Extensions are not announced by the server
* [GH-329] fix S_IFMT value on windows, plan9 and js/wasm
* [GH-325] Request.Attributes() panics when called with the Attr slice empty
* [GH-309] fix: received packet too long

Thanks to all the contributors. Your time and patience is appreciated.