Set a custom user-agent for requests

This is now formatted as:

`commercetools-python-sdk/2022.6.4 Python/3.10 (cpython; darwin; arm64)`

Author: mvantellingen

src/commercetools/base_client.py

@@ -1,19 +1,17 @@
-import io
 import os
+import platform
+import sys
 import typing
-import urllib.parse
 
-import requests
-from marshmallow.base import SchemaABC
 from oauthlib.oauth2 import BackendApplicationClient
 from requests.adapters import HTTPAdapter
 from requests_oauthlib import OAuth2Session
 from urllib3 import Retry
 
+from commercetools.version import __version__
 from commercetools.constants import HEADER_CORRELATION_ID
 from commercetools.exceptions import CommercetoolsError
 from commercetools.helpers import _concurrent_retry
-from commercetools.protocols import Model
 from commercetools.services import ServicesMixin
 from commercetools.utils import BaseTokenSaver, DefaultTokenSaver, fix_token_url
 
@@ -90,6 +88,7 @@ def __init__(
             },
             token_updater=self._save_token,
         )
+        self._http_client.headers.update({'User-Agent': self._get_user_agent()})
 
         if not http_adapter:
             # Register retry handling for Connection errors and 502, 503, 504.
@@ -223,6 +222,12 @@ def _read_env_vars(self, config: dict) -> dict:
 
         return config
 
+    def _get_user_agent(self):
+        py_version =  "%d.%d" % sys.version_info[0:2]
+        arch = platform.machine()
+        return "commercetools-python-sdk/%s Python/%s (%s; %s; %s)" % (
+            __version__, py_version, sys.implementation.name, sys.platform, arch)
+
 
 class Client(BaseClient, ServicesMixin):
     def __init__(self, *args, **kwargs):