chapters/mitigations-and-defensive-strategies: Add Dockerfile for 04-rwslotmachine4

[gabrielmocanu]

Description:

Create a Dockerfile for 04-rwslotmachine4 exercise.

Requirements:

1. Use a multi-stage Dockerfile:

• Build Stage:
  - Compile the provided C code into an executable.
• Runtime Stage:
  - Run the compiled executable and ensure it listens or operates on port 31347.

2. Verify the functionality of the solution to ensure that it works as expected after building and running the Dockerfile.

3. Ensure the Dockerfile is optimized and avoids unnecessary layers.

Expected Outcome:

A fully working Dockerfile that can be built and executed in two separate stages, satisfying the above requirements.

[AmaliaI12]

Hello! I'm working on this issue. I made the Dockerfile, but the flag isn't showing up. I'll take another look to figure out what's wrong.