Get test_licenses using pkg_info ala liccheck

Fixes #2

tools/python/BUILD

@@ -1,7 +1,9 @@
 load("@rules_python//python:defs.bzl",
-     "py_runtime_pair"
+     "py_runtime_pair",
 )
 
+load("@arrdem_source_pypi//:requirements.bzl", "all_requirements")
+
 package(default_visibility = ["//visibility:public"])
 
 licenses(["notice"])
@@ -40,8 +42,5 @@ py_pytest(
     data = [
         "requirements.txt",
     ],
-    deps = [
-        py_requirement("requests"),
-        py_requirement("requirements-parser"),
-    ]
+    deps = all_requirements,
 )