Fix Travis caching build artifacts
Fix Travis caching build artifacts

bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode,bertptrs/adventofcode