scripts/updatebom: remove innecessary mod override

The `GOFLAGS=-mod=mod` environment variable is not required, as that's
the default mode. This code was likely copied from the tests, where
`GOFLAGS` is set to `-mod=readonly`. So, executing the tool needs to
override `mod`, as per the documentation, it tends to modify the
`go.mod` file.

Signed-off-by: Ivan Valdes <ivan@vald.es>

Author: ivanvc

scripts/updatebom.sh

@@ -14,7 +14,7 @@ function bom_fixlet {
   # shellcheck disable=SC2207
   modules=($(modules_for_bom))
 
-  if GOFLAGS=-mod=mod run_go_tool "github.com/appscodelabs/license-bill-of-materials" \
+  if run_go_tool "github.com/appscodelabs/license-bill-of-materials" \
       --override-file ./bill-of-materials.override.json \
       "${modules[@]}" > ./bill-of-materials.json.tmp; then
     cp ./bill-of-materials.json.tmp ./bill-of-materials.json