Update boringssl digest to 6c7729b

Author: renovate[bot]

bazel/zetasql_deps_step_2.bzl

@@ -218,10 +218,10 @@ py_library(
                 name = "boringssl",
                 # Commit from 2021-11-01
                 urls = [
-                    "https://github.com/google/boringssl/archive/4fb158925f7753d80fb858cb0239dff893ef9f15.tar.gz",
+                    "https://github.com/google/boringssl/archive/6c7729b88a69cf9c090a874c45177c0f2af2bab3.tar.gz",
                 ],
-                sha256 = "e168777eb0fc14ea5a65749a2f53c095935a6ea65f38899a289808fb0c221dc4",
-                strip_prefix = "boringssl-4fb158925f7753d80fb858cb0239dff893ef9f15",
+                sha256 = "e0ae351eddddac02bef4a2636999631baba76b0b7c082c529c10807a4901abae",
+                strip_prefix = "boringssl-6c7729b88a69cf9c090a874c45177c0f2af2bab3",
             )
 
         # Farmhash