fix: use explicit None checks for client config to respect zero values

The or operator treats 0 as falsy, so passing max_retries=0 (no retries),
timeout_secs=0, or min_delay_between_retries_millis=0 would silently fall
back to the default values. Changed to explicit 'is not None' checks.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vdusek

src/apify_client/client.py

@@ -89,9 +89,11 @@ def __init__(
         self.base_url = f'{api_url}/{API_VERSION}'
         api_public_url = (api_public_url or DEFAULT_API_URL).rstrip('/')
         self.public_base_url = f'{api_public_url}/{API_VERSION}'
-        self.max_retries = max_retries or 8
-        self.min_delay_between_retries_millis = min_delay_between_retries_millis or 500
-        self.timeout_secs = timeout_secs or DEFAULT_TIMEOUT
+        self.max_retries = max_retries if max_retries is not None else 8
+        self.min_delay_between_retries_millis = (
+            min_delay_between_retries_millis if min_delay_between_retries_millis is not None else 500
+        )
+        self.timeout_secs = timeout_secs if timeout_secs is not None else DEFAULT_TIMEOUT
 
     def _options(self) -> dict:
         return {