deskutils/noti: Update to 3.2.0

• Switch to GO modules-aware build mode as the port uses various modules.

Changelog:

Added:

• Support for Mattermost.
• Support for Slack App URL.
• Support for pollPID for BSD and Windows.

Removed:

• Installation by go get, can revisit in Go 1.14.

Fixed:

• Incorrect deprecation mapping.

https://github.com/variadico/noti/releases/tag/3.2.0

PR: 238842
Submitted by: Hiroki Tagato <tagattie@yandex.com> (maintainer)
Reviewed by: danfe