Make target_platforms a keyword argument

The `pypi_repo_name` function was using `*target_platforms` to accept a
variable number of positional arguments.

This is changed to a keyword argument `target_platforms` with a default
value of empty string, making the function signature more explicit and
the call site clearer.

Author: hartikainen

python/private/pypi/extension.bzl

@@ -420,7 +420,7 @@ def _whl_repo(
             return struct(
                 repo_name = pypi_repo_name(
                     normalize_name(src.distribution),
-                    *target_platforms
+                    target_platforms = target_platforms,
                 ),
                 args = args,
                 config_setting = whl_config_setting(

python/private/pypi/whl_repo_name.bzl

@@ -61,19 +61,17 @@ def whl_repo_name(filename, sha256):
 
     return "_".join(parts)
 
-def pypi_repo_name(whl_name, *target_platforms):
+def pypi_repo_name(whl_name, target_platforms=[]):
     """Return a valid whl_library given a requirement line.
 
     Args:
         whl_name: {type}`str` the whl_name to use.
-        *target_platforms: {type}`list[str]` the target platforms to use in the name.
+        target_platforms: {type}`list[str]` the target platforms to use in the name.
 
     Returns:
         {type}`str` that can be used in {obj}`whl_library`.
     """
-    parts = [
-        normalize_name(whl_name),
-    ]
+    parts = [normalize_name(whl_name)]
     parts.extend([p.partition("_")[-1] for p in target_platforms])
 
     return "_".join(parts)