Add headers to download queries to workaround readthedocs/readthedocs…

….org#11763

src/input4mips_validation/cvs/loading_raw.py

@@ -113,7 +113,9 @@ class RawCVLoaderKnownRemoteRegistry:
     Whether to force a new download of the file if it already exists
     """
 
-    def load_raw(self, filename: str) -> str:
+    def load_raw(
+        self, filename: str, downloader: pooch.HTTPDownloader | None = None
+    ) -> str:
         """
         Load raw CV data
 
@@ -122,6 +124,11 @@ def load_raw(self, filename: str) -> str:
         filename
             Filename from which to load raw CV data
 
+        downloader
+            Downloader to use when fetching.
+
+            If not supplied, we use a basic default HTTP downloader.
+
         Returns
         -------
             Raw CV data
@@ -131,7 +138,13 @@ def load_raw(self, filename: str) -> str:
             if expected_out_file.exists():
                 expected_out_file.unlink()
 
-        with open(Path(self.registry.fetch(filename))) as fh:
+        if downloader is None:
+            downloader = pooch.HTTPDownloader(
+                # https://github.com/readthedocs/readthedocs.org/issues/11763
+                headers={"User-Agent": "input4mips-validation"}
+            )
+
+        with open(Path(self.registry.fetch(filename, downloader=downloader))) as fh:
             raw = fh.read()
 
         return raw