Exclude localhost from hitting proxies for metadata service requests

`requests` package doesn't do it by default.

Relevant issue: databricks/databricks-vscode#916 (comment)

Author: ilia-db

databricks/sdk/credentials_provider.py

@@ -681,6 +681,11 @@ def refresh(self) -> Token:
                             headers={
                                 self.METADATA_SERVICE_VERSION_HEADER: self.METADATA_SERVICE_VERSION,
                                 self.METADATA_SERVICE_HOST_HEADER: self.host
+                            },
+                            proxies={
+                                # Metadata URL usually points to localhost, so we need to exclude it from proxy
+                                # as the requests package doesn't exclude localhost from proxies by default
+                                "no_proxy": "localhost,127.0.0.1"
                             })
         json_resp: dict[str, Union[str, float]] = resp.json()
         access_token = json_resp.get("access_token", None)