fix: add api_token parameter to copy() methods for consistency

The copy() methods in Replicate and AsyncReplicate were missing the
api_token parameter that was added to __init__ in commit 8c05e64. This
was causing test failures since the test suite expects the copy() method
signature to match the constructor signature.

This commit adds the api_token parameter to both copy() methods with the
same handling logic as in __init__:
- Accepts both api_token and bearer_token
- Raises error if both are provided
- Maps api_token to bearer_token internally

Author: zeke

src/replicate/_client.py

@@ -334,6 +334,7 @@ def use(
     def copy(
         self,
         *,
+        api_token: str | None = None,
         bearer_token: str | None = None,
         base_url: str | httpx.URL | None = None,
         timeout: float | Timeout | None | NotGiven = NOT_GIVEN,
@@ -348,6 +349,15 @@ def copy(
         """
         Create a new client instance re-using the same options given to the current client with optional overriding.
         """
+        # Handle api_token as legacy alias for bearer_token
+        if api_token is not None and bearer_token is not None:
+            raise ValueError(
+                "Cannot provide both api_token and bearer_token parameters. "
+                "Use bearer_token (api_token is deprecated)."
+            )
+        if api_token is not None:
+            bearer_token = api_token
+            
         if default_headers is not None and set_default_headers is not None:
             raise ValueError("The `default_headers` and `set_default_headers` arguments are mutually exclusive")
 
@@ -720,6 +730,7 @@ def use(
     def copy(
         self,
         *,
+        api_token: str | None = None,
         bearer_token: str | None = None,
         base_url: str | httpx.URL | None = None,
         timeout: float | Timeout | None | NotGiven = NOT_GIVEN,
@@ -734,6 +745,15 @@ def copy(
         """
         Create a new client instance re-using the same options given to the current client with optional overriding.
         """
+        # Handle api_token as legacy alias for bearer_token
+        if api_token is not None and bearer_token is not None:
+            raise ValueError(
+                "Cannot provide both api_token and bearer_token parameters. "
+                "Use bearer_token (api_token is deprecated)."
+            )
+        if api_token is not None:
+            bearer_token = api_token
+            
         if default_headers is not None and set_default_headers is not None:
             raise ValueError("The `default_headers` and `set_default_headers` arguments are mutually exclusive")