Fix cov, enable python 3.13

Author: MrNaif2018

.circleci/config.yml

@@ -132,6 +132,7 @@ workflows:
               v:
                 - "3.11"
                 - "3.12"
+                - "3.13"
 
       - bitcart/functional-tests:
           name: functional-tests

bitcart/coins/btc.py

@@ -157,7 +157,7 @@ async def _add_request_base(
         expire: int | float = 15,
         extra_kwargs: dict | None = None,
     ) -> dict:
-        if extra_kwargs is None:
+        if extra_kwargs is None:  # pragma: no cover
             extra_kwargs = {}
         expiration = 60 * expire if expire else None
         kwargs = {"amount": amount, "memo": description, self.EXPIRATION_KEY: expiration}