go.mod: tell x repo tagging to ignore dep on net

CL 475438 introduced a cycle between net and crypto. This direction is
less important, so have the tagging process ignore it.

Change-Id: Ie424fef0238702a5a16aba79bb60f86f39dc66eb
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/502595
Auto-Submit: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>

go.mod

@@ -3,7 +3,7 @@ module golang.org/x/crypto
 go 1.17
 
 require (
-	golang.org/x/net v0.10.0
+	golang.org/x/net v0.10.0 // tagx:ignore
 	golang.org/x/sys v0.8.0
 	golang.org/x/term v0.8.0
 )