Bump ubuntu from `40b84b7` to `ca70a83` in /release (#2272)

diff --git a/release/DOCKERFILE b/release/DOCKERFILE
index 9b763b6..77bf29d 100644
--- a/release/DOCKERFILE
+++ b/release/DOCKERFILE
@@ -1,4 +1,4 @@
-FROM ubuntu:bionic@sha256:40b84b75884ff39e4cac4bf62cb9678227b1fbf9dbe3f67ef2a6b073aa4bb529
+FROM ubuntu:bionic@sha256:ca70a834041dd1bf16cc38dfcd24f0888ec4fa431e09f3344f354cf8d1724499
 RUN apt update
 RUN apt install -y git
 RUN git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git