chore: surround final variable values in double quotes

Author: diegomarquezp

.github/scripts/hermetic_library_generation.sh

@@ -106,11 +106,11 @@ if [[ "${showcase_mode}" == "true" ]]; then
 fi
 
 # get changed library list.
-changed_libraries_file=$(mktemp)
+changed_libraries_file="$(mktemp)"
 python hermetic_build/common/cli/get_changed_libraries.py create \
   --baseline-generation-config-path="${baseline_generation_config}" \
   --current-generation-config-path="${generation_config}" | tee "${changed_libraries_file}"
-changed_libraries=$(cat "${changed_libraries_file}")
+changed_libraries="$(cat "${changed_libraries_file}")"
 echo "Changed libraries are: ${changed_libraries:-"No changed library"}."
 
 # run hermetic code generation docker image.