all.bash: add go mod tidy

Change-Id: I7ebdb44dc2c8208f9fabafe0a3e58247660297c0
Reviewed-on: https://go-review.googlesource.com/c/vulndb/+/357010
Trust: Julie Qiu <julie@golang.org>
Run-TryBot: Julie Qiu <julie@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Roland Shoemaker <roland@golang.org>

all.bash

@@ -62,6 +62,10 @@ go_linters() {
   check_unparam
 }
 
+go_modtidy() {
+  runcmd go mod tidy
+}
+
 go_test() {
   runcmd go test ./...
 }
@@ -88,6 +92,7 @@ main() {
       ;;
     "")
       go_linters
+      go_modtidy
       go_test
       ;;
     *)