exec_compatible_with -> target_compatible_with #704 (#747)

python/private/toolchains_repo.bzl

diff --git a/python/private/toolchains_repo.bzl b/python/private/toolchains_repo.bzl
index 14576bc..282859a 100644
--- a/python/private/toolchains_repo.bzl
+++ b/python/private/toolchains_repo.bzl
@@ -48,7 +48,7 @@
 # for executing build actions.
 toolchain(
     name = "{platform}_toolchain",
-    exec_compatible_with = {compatible_with},
+    target_compatible_with = {compatible_with},
     toolchain = "@{user_repository_name}_{platform}//:python_runtimes",
     toolchain_type = "@bazel_tools//tools/python:toolchain_type",
 )