fix: Resolve race condition in HTTP server handling

[daveads]

fix: Resolve race condition in HTTP server handling

• Implement thread-safe safeServer to wrap http.Server
• Modify Serve function to use safeServer for improved concurrency
• Ensure atomic operations for server start and shutdown

This change addresses a race condition in the HTTP server handling,particularly affecting CLI tests. By introducing a safeServer struct with atomic operations and proper synchronization, and prevent potential data races during server startup and shutdown.

Fix for terrastruct/d2#2087

[daveads]

@alixander change the current version of golang to fix the ci failing test

Use actions/setup-go@v4 instead of actions/setup-go@v3

[daveads]

@alixander should i just replace atomic.Bool with atomic.Int32 which is support by go v1.18

[daveads]

@alixander your attention is needed here.

[alixander]

i've bumped the setup-go action in master, please rebase

[daveads]

@alixander ready for merge...

[alixander]

this is just another way of doing what you did in the last PR right? Can you revert the last PR's changes then