core: use token in auth in subsequent requests

if a token was saved in auth,
it shall be used in subsequent requests.

This avoid a situation where:
to upload a blob, first is done anonymously, then
retry with token
then upload a manifest, avoid the attempt to upload
anonymously if a token was present in the previous
flow

Signed-off-by: tarilabs <matteo.mortari@gmail.com>

oras/provider.py

@@ -927,7 +927,9 @@ def do_request(
         :param stream: stream the responses
         :type stream: bool
         """
-        # Make the request and return to calling function, unless requires auth
+        # Make the request and return to calling function, but attempt to use auth token if previously obtained
+        if isinstance(self.auth, oras.auth.TokenAuth):
+            headers.update(self.auth.get_auth_header())
         response = self.session.request(
             method,
             url,