go.mod: update to latest go-cmdtest

Update to go-cmdtest v0.4.0 to fix a bug.

Change-Id: I001364cc9f7c644f81ea4665a5655678351bda22
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/399475
Run-TryBot: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
diff --git a/go.mod b/go.mod
index e9610e4..4c04545 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,7 @@
 
 require (
 	github.com/client9/misspell v0.3.4
-	github.com/google/go-cmdtest v0.3.0
+	github.com/google/go-cmdtest v0.4.0
 	github.com/google/go-cmp v0.5.6
 	golang.org/x/mod v0.6.0-dev.0.20211013180041-c96bc1413d57
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
diff --git a/go.sum b/go.sum
index 301a878..1b96cc1 100644
--- a/go.sum
+++ b/go.sum
@@ -2,8 +2,8 @@
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/client9/misspell v0.3.4 h1:ta993UF76GwbvJcIo3Y68y/M3WxlpEHPWIGDkJYwzJI=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
-github.com/google/go-cmdtest v0.3.0 h1:382oNMtKBpvJjOm5c5ONU3pzwh2ZK/eNA4/h2v9PnXM=
-github.com/google/go-cmdtest v0.3.0/go.mod h1:apVn/GCasLZUVpAJ6oWAuyP7Ne7CEsQbTnc0plM3m+o=
+github.com/google/go-cmdtest v0.4.0 h1:ToXh6W5spLp3npJV92tk6d5hIpUPYEzHLkD+rncbyhI=
+github.com/google/go-cmdtest v0.4.0/go.mod h1:apVn/GCasLZUVpAJ6oWAuyP7Ne7CEsQbTnc0plM3m+o=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=