Bump github.com/mattermost/mattermost-server/v6 from 6.1.0 to 6.3.0 (#1686)

Bumps [github.com/mattermost/mattermost-server/v6](https://github.com/mattermost/mattermost-server) from 6.1.0 to 6.3.0.
- [Release notes](https://github.com/mattermost/mattermost-server/releases)
- [Changelog](https://github.com/mattermost/mattermost-server/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mattermost/mattermost-server/compare/v6.1.0...v6.3.0)

---
updated-dependencies:
- dependency-name: github.com/mattermost/mattermost-server/v6
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

vendor/golang.org/x/sys/unix/syscall_dragonfly.go

@@ -101,7 +101,10 @@ func Pipe(p []int) (err error) {
 	if len(p) != 2 {
 		return EINVAL
 	}
-	p[0], p[1], err = pipe()
+	r, w, err := pipe()
+	if err == nil {
+		p[0], p[1] = r, w
+	}
 	return
 }
 
@@ -114,7 +117,10 @@ func Pipe2(p []int, flags int) (err error) {
 	var pp [2]_C_int
 	// pipe2 on dragonfly takes an fds array as an argument, but still
 	// returns the file descriptors.
-	p[0], p[1], err = pipe2(&pp, flags)
+	r, w, err := pipe2(&pp, flags)
+	if err == nil {
+		p[0], p[1] = r, w
+	}
 	return err
 }