add a missing BUILD.bazel file for integration tests

Author: aignas

python/BUILD.bazel

@@ -43,6 +43,7 @@ filegroup(
         "//python/pip_install:distribution",
         "//python/private:distribution",
         "//python/runfiles:distribution",
+        "//python/runtime_env_toolchains:distribution",
         "//python/uv:distribution",
     ],
     visibility = ["//:__pkg__"],

python/runtime_env_toolchains/BUILD.bazel

@@ -17,3 +17,9 @@ load("//python/private:runtime_env_toolchain.bzl", "define_runtime_env_toolchain
 package(default_visibility = ["//:__subpackages__"])
 
 define_runtime_env_toolchain(name = "runtime_env_toolchain")
+
+filegroup(
+    name = "distribution",
+    srcs = glob(["**"]),
+    visibility = ["//python:__pkg__"],
+)