Fix outdated instructions (#1000)

test/deps.bzl

diff --git a/test/deps.bzl b/test/deps.bzl
index 1bd279a..58c09bc 100644
--- a/test/deps.bzl
+++ b/test/deps.bzl
@@ -5,7 +5,7 @@
 load("//test/load_arbitrary_tool:load_arbitrary_tool_test.bzl", "load_arbitrary_tool_test")
 
 _LIBC_BUILD_FILE_CONTENT = """\
-load("@rules_rust//rust:rust.bzl", "rust_library")
+load("@rules_rust//rust:defs.bzl", "rust_library")
 
 rust_library(
     name = "libc",