USPS broken after official Rest API upgrade

[tongtian0925]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Go to shipments create a new one
2. enter sender and receiver
3. get rates returns error
4. {
   "messages": [
   {
   "carrier_id": "Pz7NrWjQhkEWU8dbP8uJUKmWu0iWGsOj",
   "carrier_name": "usps",
   "code": "SHIPPING_SDK_INTERNAL_ERROR",
   "message": "'str' object has no attribute 'get'"
   }
   ]
   }

curl:

curl 'https://xxxx.syminno.com/v1/proxy/rates'
-H 'accept: application/json, text/plain, /'
-H 'accept-language: en-US,en;q=0.9,zh-TW;q=0.8,zh-CN;q=0.7,zh;q=0.6'
-H 'authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0b2tlbl90eXBlIjoiYWNjZXNzIiwiZXhwIjoxNzMxMjAzMzIyLCJpYXQiOjE3Mjg2MTEzMjIsImp0aSI6ImIzZGZmNGY3OGVhOTRjZTk5MTAxZDgwMzljMmQ4MmJlIiwidXNlcl9pZCI6MSwiaXNfdmVyaWZpZWQiOnRydWV9.5ODf-k3Q8EpIRDJyyPzG0foIB07W30RmAnZNR2RcVhE'
-H 'content-type: application/json'
-H 'origin: https://xxxx.syminno.com'
-H 'priority: u=1, i'
-H 'referer: https://xxxx.syminno.com/'
-H 'sec-ch-ua: "Chromium";v="128", "Not;A=Brand";v="24", "Google Chrome";v="128"'
-H 'sec-ch-ua-mobile: ?0'
-H 'sec-ch-ua-platform: "Windows"'
-H 'sec-fetch-dest: empty'
-H 'sec-fetch-mode: cors'
-H 'sec-fetch-site: same-site'
-H 'user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36'
-H 'x-test-mode: true'
--data-raw '{"shipper":{"person_name":"Matt","address_line1":"602 Surf Ave","country_code":"US","postal_code":"11224","city":"Brooklyn","state_code":"NY"},"recipient":{"country_code":"US","address_line1":"145 Brooklyn Ave","city":"Brooklyn","postal_code":"11213","state_code":"NY","person_name":"Zack"},"parcels":[{"weight":1,"width":33.7,"height":18.2,"length":10,"is_document":false,"packaging_type":"your_packaging","weight_unit":"KG","dimension_unit":"CM","items":[]}],"options":{"shipping_date":"2024-10-10T21:55"},"payment":{"paid_by":"sender"},"label_type":"PDF"}'

Expected behavior
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Screenshots

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Additional context
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[tongtian0925]

take a deep investigation, there are many issues for the usps integration

for example:

• auth is not working because client id and secret is not passed to login
  https://github.com/karrioapi/karrio/blob/main/modules/connectors/usps/karrio/providers/usps/utils.py#L50

• USPS API document has been changed ,all the proxy apis are changed, USPS add a prefix to that.
  get rate API, in the code we have url=f"{self.settings.server_url}/v3/total-rates/search", but the actually API has been changed to https://api.usps.com/**prices**/v3/total-rates/search

• some API auth Bearer token + payment auth token, X-Payment-Authorization-Token

USPS API reference: https://developer.usps.com/apis