pmb.helpers.http: Simplify retrieve_json() (MR 2490)

The parameters of this function were needlessly complicated. While I
understand the intent of trying to replicate the API of retrieve()
without duplicating the parameter list, in practice this feels like
reducing duplication to a fault to me. This is due to that the third
parameter, <allow_404>, doesn't make sense in the context of
retrieve_json() as it would raise an exception[1] if retrieve() returns
None (which is the effect of <allow_404> when a 404 occurs), thus merely
changing the exception that gets raised to a less descriptive one
instead of actually behaving like retrieve() would with that parameter
set to True.

With <allow_404> eliminated, there's just two parameters left, and I
don't think duplicating those is a big deal. So make the function easier
to read and annotate by getting rid of the args/kwargs logic.

 [1]: json.loads() raises an exception if its first argument is None

pmb/helpers/http.py

@@ -7,7 +7,7 @@ import os
 from pathlib import Path
 import shutil
 import urllib.request
-from typing import Literal, overload
+from typing import Any, Literal, overload
 import pmb.helpers.cli
 
 from pmb.core.context import get_context
@@ -143,9 +143,9 @@ def retrieve(
         raise
 
 
-def retrieve_json(*args, **kwargs):
+def retrieve_json(url: str, headers: dict[str, str] | None = None) -> Any:
     """Fetch the contents of a URL, parse it as JSON and return it.
 
-    See retrieve() for the list of all parameters.
+    See retrieve() for the meaning of the parameters.
     """
-    return json.loads(retrieve(*args, **kwargs))
+    return json.loads(retrieve(url, headers, False))