Bazel: update zlib to v1.2.12.

Change-Id: I221e8039b97e333c94a5a4c0329aec926b2745cd
Signed-off-by: Piotr Sikora <piotrsikora@google.com>
Reviewed-on: https://nginx-review.googlesource.com/c/nginx/+/4000
Reviewed-by: Patryk Lesiewicz <patryk@google.com>

bazel/repositories.bzl

diff --git a/bazel/repositories.bzl b/bazel/repositories.bzl
index 403a5c6..0bb5b15 100644
--- a/bazel/repositories.bzl
+++ b/bazel/repositories.bzl
@@ -66,9 +66,9 @@
     http_archive(
         name = "zlib",
         build_file = "@nginx//bazel/external:zlib.BUILD",
-        sha256 = "c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1",
-        strip_prefix = "zlib-1.2.11",
-        url = "https://zlib.net/zlib-1.2.11.tar.gz",
+        sha256 = "91844808532e5ce316b3c010929493c0244f3d37593afd6de04f71821d5136d9",
+        strip_prefix = "zlib-1.2.12",
+        url = "https://zlib.net/zlib-1.2.12.tar.gz",
     )
 
     # ngx_brotli + dependencies