Support 32-bit Python/Windows by using `@platforms`.

Fixes #53.

py/BUILD.tpl

diff --git a/py/BUILD.tpl b/py/BUILD.tpl
index 653fe38..7c06d41 100644
--- a/py/BUILD.tpl
+++ b/py/BUILD.tpl
@@ -35,7 +35,7 @@
 cc_import(
     name = "python_lib",
     interface_library = select({
-        ":windows": ":python_import_lib",
+        "@platforms//os:windows": ":python_import_lib",
         # A placeholder for Unix platforms which makes --no_build happy.
         "//conditions:default": "not-existing.lib",
     }),
@@ -46,7 +46,7 @@
     name = "python_headers",
     hdrs = [":python_include"],
     deps = select({
-        ":windows": [":python_lib"],
+        "@platforms//os:windows": [":python_lib"],
         "//conditions:default": [],
     }),
     includes = ["python_include"],
@@ -56,7 +56,7 @@
     name = "python_embed",
     hdrs = [":python_include"],
     deps = select({
-        ":windows": [":python_lib"],
+        "@platforms//os:windows": [":python_lib"],
         "//conditions:default": [],
     }),
     includes = ["python_include"],
@@ -64,11 +64,5 @@
     copts = ["%{PYTHON_EMBED_COPTS}"],
 )
 
-config_setting(
-    name = "windows",
-    values = {"cpu": "x64_windows"},
-    visibility = ["//visibility:public"],
-)
-
 %{PYTHON_INCLUDE_GENRULE}
 %{PYTHON_IMPORT_LIB_GENRULE}