ipn/ipnlocal: fix fmt format arg type mismatch in log line

It was printing like "v0xxxxxxxx" after version.Long became a func
in 8b2ae47c31.

Fixes #7976

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/ipnlocal/local.go

@@ -2479,7 +2479,7 @@ func (b *LocalBackend) parseWgStatusLocked(s *wgengine.Status) (ret ipn.EngineSt
 	// [GRINDER STATS LINES] - please don't remove (used for log parsing)
 	if peerStats.Len() > 0 {
 		b.keyLogf("[v1] peer keys: %s", strings.TrimSpace(peerKeys.String()))
-		b.statsLogf("[v1] v%v peers: %v", version.Long, strings.TrimSpace(peerStats.String()))
+		b.statsLogf("[v1] v%v peers: %v", version.Long(), strings.TrimSpace(peerStats.String()))
 	}
 	return ret
 }