chore: remove alpine container references

[lucarlig]

📌 Summary

This updates the builder compose test fixture to use redis:7-bookworm instead of redis:7-alpine.

🔁 Reproduction Steps

1. Inspect tests/unit/mcpgateway/tools/builder/test_common.py.
2. Find the compose infrastructure test fixture that still uses redis:7-alpine.
3. Compare with the main Rust CI branch work, which already moved branch-local Redis services off Alpine.

🐞 Root Cause

The test fixture still referenced Alpine-based Redis even though the active CI/container changes are moving Redis service images away from Alpine.

💡 Fix Description

Replaced the fixture value with redis:7-bookworm. No production code changed.

🧪 Verification

Check	Command	Status
Focused unit test	uv run pytest -q tests/unit/mcpgateway/tools/builder/test_common.py -k infrastructure	✅

📐 MCP Compliance (if relevant)

• Matches current MCP spec
• No breaking change to MCP clients

✅ Checklist

• Code formatted (make black isort pre-commit)
• No secrets/credentials committed