fix: remove obsolete version field from docker-compose.yml

[xu826Jamin]

Summary

Removes the deprecated version field from docker-compose.yml.

Problem

The version field is obsolete in recent versions of Docker Compose
and generates the following warning on every run:

the attribute version is obsolete, it will be ignored, please remove
it to avoid potential confusion

Solution

Removed the version: "3" line from docker-compose.yml.

Fixes #81

[Copilot]

Pull request overview

Removes the deprecated top-level version field from docker-compose.yml to eliminate the Docker Compose warning described in #81.

Changes:

• Removed version: "3" from docker-compose.yml.

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[xu826Jamin]

Hi @Shubh942! I'm Jamin, a 2nd year Computer Engineering student interested in GDB-UI for GSoC 2026. I just submitted PR #172. I'd love to join the C2SI Slack to connect with the community — could you share a fresh invite link? Thanks!