semver: basic semver parsing package

Copied from cmd/go/internal/semver.

For golang/go#31761.

Change-Id: I59e8a264f49a5d20ba1caa85b59c3177209a6ff5
Reviewed-on: https://go-review.googlesource.com/c/mod/+/176460
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
3 files changed
tree: ad8a5e4cd7693baa2f1079ed1cc62808358be96b
  1. LICENSE
  2. PATENTS
  3. README
  4. codereview.cfg
  5. go.mod
  6. semver/