Add server header option to dev and run commands

[smarcelloc]

Security Enhancement: Server Header Control in FastAPI CLI

Problem Context

Uvicorn, by default, includes the "Server: uvicorn" header in all HTTP responses. This information represents a security risk because:

1. It exposes technical details about the infrastructure (Uvicorn server => Python)
2. It makes it easier for potential attackers to identify the technology being used
3. It can be used to target specific attacks knowing the underlying technology

Before

Now

Solution Implemented

Added a new --server-header option to the fastapi dev and fastapi run commands, which:

• Is disabled by default (False), removing the "Server: uvicorn" header from responses
• When explicitly enabled (--server-header), maintains the original behavior

How to Use

To maintain the original behavior (show the server header):

fastapi dev --server-header
# or
fastapi run --server-header