[Bazel] Update zlib to 1.2.12

There's a vulnerability in 1.2.11:
https://twitter.com/taviso/status/1508438583484452866

Differential Revision: https://reviews.llvm.org/D122619

Author: GMNGeoffrey

utils/bazel/WORKSPACE

@@ -38,10 +38,10 @@ maybe(
     name = "zlib",
     build_file = "@llvm-raw//utils/bazel/third_party_build:zlib.BUILD",
     sha256 = "c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1",
-    strip_prefix = "zlib-1.2.11",
+    strip_prefix = "zlib-1.2.12",
     urls = [
-        "https://storage.googleapis.com/mirror.tensorflow.org/zlib.net/zlib-1.2.11.tar.gz",
-        "https://zlib.net/zlib-1.2.11.tar.gz",
+        "https://storage.googleapis.com/mirror.tensorflow.org/zlib.net/zlib-1.2.12.tar.gz",
+        "https://zlib.net/zlib-1.2.12.tar.gz",
     ],
 )