Explicitly load default certificates when creating SSL context (httpie#1583)

Requests prior to 2.32.3 always loaded the default (system-wide)
set of trusted certificates into custom SSL contexts. 2.32.3 no
longer does. This has broken a lot of users, but the fix is
moving slowly upstream due to security considerations - see
psf/requests#6730 and
psf/requests#6731 .

As suggested at
psf/requests#6710 (comment)
this can be worked around by explicitly loading the default
certificates into the context. We check the method exists before
calling it just to be safe, but I'm pretty sure it's been there
as long as this interface has existed.

Signed-off-by: Adam Williamson <[email protected]>

Author: AdamWill

httpie/ssl_.py

@@ -48,6 +48,8 @@ def __init__(
             ssl_version=ssl_version,
             ciphers=ciphers,
         )
+        if getattr(self._ssl_context, 'load_default_certs', None) is not None:
+            self._ssl_context.load_default_certs()
         super().__init__(**kwargs)
 
     def init_poolmanager(self, *args, **kwargs):