github/govuln: don't swallow govulncheck errors

By running `find -exec`, an error exit code doesn't properly return the
error if there's a failure in a command executed. Use `xargs` to force
an exit with error when a command fails to run.

Signed-off-by: Ivan Valdes <[email protected]>

.github/workflows/govuln.yaml

@@ -18,4 +18,4 @@ jobs:
 
           go install golang.org/x/vuln/cmd/govulncheck@latest
 
-          find -name go.mod -exec /bin/bash -c 'echo scanning $(dirname {}); govulncheck -C $(dirname {}) -show verbose ./...' \;
+          find . -name go.mod | xargs -I'{}' /bin/bash -c 'echo scanning $(dirname {}); govulncheck -C $(dirname {}) -show verbose ./...'