melange pipeline working-directory could allow command injection

melange allows users to build apk packages using declarative pipelines. From version 0.3.0 to before 0.40.3, an attacker who can provide build input values, but not modify pipeline definitions, could execute arbitrary shell commands if the pipeline uses ${{vars.*}} or ${{inputs.*}} substitutions in working-directory. The field is embedded into shell scripts without proper quote escaping. This issue has been patched in version 0.40.3.