Respect `resume_download` deprecation (#30620)

* Deprecate resume_download

* remove default resume_download value

---------
Co-authored-by: Lysandre Debut <hi@lysand.re>

src/transformers/utils/peft_utils.py

@@ -30,7 +30,7 @@ def find_adapter_config_file(
     model_id: str,
     cache_dir: Optional[Union[str, os.PathLike]] = None,
     force_download: bool = False,
-    resume_download: bool = False,
+    resume_download: Optional[bool] = None,
     proxies: Optional[Dict[str, str]] = None,
     token: Optional[Union[bool, str]] = None,
     revision: Optional[str] = None,
@@ -51,8 +51,9 @@ def find_adapter_config_file(
         force_download (`bool`, *optional*, defaults to `False`):
             Whether or not to force to (re-)download the configuration files and override the cached versions if they
             exist.
-        resume_download (`bool`, *optional*, defaults to `False`):
-            Whether or not to delete incompletely received file. Attempts to resume the download if such a file exists.
+        resume_download:
+            Deprecated and ignored. All downloads are now resumed by default when possible.
+            Will be removed in v5 of Transformers.
         proxies (`Dict[str, str]`, *optional*):
             A dictionary of proxy servers to use by protocol or endpoint, e.g., `{'http': 'foo.bar:3128',
             'http://hostname': 'foo.bar:4012'}.` The proxies are used on each request.