Update rules_docker to latest release

Fixes compatibility issues with newer Python versions

Change-Id: I55a118fd391bef45017501e77284adda5186d1ff
Reviewed-on: https://cos-review.googlesource.com/c/cos/tools/+/35947
Tested-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Cloud-Build: GCB Service account <228075978874@cloudbuild.gserviceaccount.com>
Reviewed-by: Nobel Barakat <nobelbarakat@google.com>
diff --git a/WORKSPACE b/WORKSPACE
index cc0ad52..8b5ffbc 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -36,9 +36,9 @@
 
 http_archive(
     name = "io_bazel_rules_docker",
-    sha256 = "4521794f0fba2e20f3bf15846ab5e01d5332e587e9ce81629c7f96c793bb7036",
-    strip_prefix = "rules_docker-0.14.4",
-    urls = ["https://github.com/bazelbuild/rules_docker/archive/v0.14.4.tar.gz"],
+    sha256 = "07ee8ca536080f5ebab6377fc6e8920e9a761d2ee4e64f0f6d919612f6ab56aa",
+    strip_prefix = "rules_docker-0.25.0",
+    urls = ["https://github.com/bazelbuild/rules_docker/archive/v0.25.0.tar.gz"],
 )
 
 http_archive(
@@ -112,10 +112,6 @@
 
 container_deps()
 
-load("@io_bazel_rules_docker//repositories:pip_repositories.bzl", "pip_deps")
-
-pip_deps()
-
 load(
     "@io_bazel_rules_docker//container:container.bzl",
     "container_pull",