use full path in backend_pb2 import

pylib/tools/BUILD.bazel

@@ -28,9 +28,6 @@ py_binary(
         "genbackend.py",
         "//pylib/anki:backend_pb2",
     ],
-    imports = [
-        "../anki",
-    ],
     visibility = ["//pylib:__subpackages__"],
     deps = [
         requirement("black"),

pylib/tools/genbackend.py

@@ -5,9 +5,10 @@ import os
 import re
 import sys
 
-import backend_pb2 as pb
 import stringcase
 
+import pylib.anki.backend_pb2 as pb
+
 TYPE_DOUBLE = 1
 TYPE_FLOAT = 2
 TYPE_INT64 = 3