make update: Use a shell array instead of string

hack/make-rules/update.sh

@@ -35,7 +35,7 @@ if ! ${ALL} ; then
 	echo "Running in short-circuit mode; run with FORCE_ALL=true to force all scripts to run."
 fi
 
-BASH_TARGETS="
+BASH_TARGETS=(
 	update-generated-protobuf
 	update-codegen
 	update-generated-runtime
@@ -45,9 +45,10 @@ BASH_TARGETS="
 	update-generated-docs
 	update-generated-swagger-docs
 	update-openapi-spec
-	update-gofmt"
+	update-gofmt
+)
 
-for t in ${BASH_TARGETS}; do
+for t in "${BASH_TARGETS[@]}"; do
 	echo -e "${color_yellow:?}Running ${t}${color_norm:?}"
 	if ${SILENT} ; then
 		if ! bash "${KUBE_ROOT}/hack/${t}.sh" 1> /dev/null; then