chore(asm): fix win32 fork usage error [backport 2.1] (#7141)

Backport 4446068 from #7126 to 2.1.

Follow-up on the fix for "Mac OS X spawn bomb"
#7096

There is no "fork" context in Win32 platform, only "spawn"
Fixes Windows builds, currently broken:
https://github.com/DataDog/dd-trace-py/actions/runs/6387793629

## Checklist
- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)
- [x] If this PR touches code that signs or publishes builds or
packages, or handles credentials of any kind, I've requested a review
from `@DataDog/security-design-and-guidance`.
- [x] This PR doesn't touch any of that.

Co-authored-by: Federico Mon <[email protected]>

Author: github-actions[bot]

ddtrace/settings/config.py

@@ -2,6 +2,7 @@
 import multiprocessing
 import os
 import re
+import sys
 from typing import List
 from typing import Optional
 from typing import Tuple
@@ -191,7 +192,9 @@ class Config(object):
     available and can be updated by users.
     """
 
-    _extra_services_queue = multiprocessing.get_context("fork").Queue(512)  # type: multiprocessing.Queue
+    _extra_services_queue = multiprocessing.get_context("fork" if sys.platform != "win32" else "spawn").Queue(
+        512
+    )  # type: multiprocessing.Queue
 
     class _HTTPServerConfig(object):
         _error_statuses = "500-599"  # type: str