go.mod: update to latest certstore

It includes a fix to allow us to use Go 1.18.
We can now remove our Tailscale-only build tags.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>

go.mod

@@ -35,7 +35,7 @@ require (
 	github.com/peterbourgon/ff/v3 v3.1.2
 	github.com/pkg/sftp v1.13.4
 	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
-	github.com/tailscale/certstore v0.0.0-20210528134328-066c94b793d3
+	github.com/tailscale/certstore v0.1.1-0.20220316223106-78d6e1c49d8d
 	github.com/tailscale/depaware v0.0.0-20210622194025-720c4b409502
 	github.com/tailscale/goexpect v0.0.0-20210902213824-6e8c725cea41
 	github.com/tailscale/goupnp v1.0.1-0.20210804011211-c64d0f06ea05