ci: fix bazel/deps-cache.py (#14912)

Author: dbolduc

MODULE.bazel

@@ -43,6 +43,9 @@ bazel_dep(name = "pugixml", version = "1.14.bcr.1", dev_dependency = True, repo_
 bazel_dep(name = "zlib", version = "1.3.1.bcr.4")
 bazel_dep(name = "c-ares", version = "1.16.1", repo_name = "com_github_cares_cares")
 
+# Pin this to fix a break in bazel/deps-cache.py
+bazel_dep(name = "protoc-gen-validate", version = "1.0.4.bcr.2", dev_dependency = True, repo_name = "com_envoyproxy_protoc_gen_validate")
+
 python = use_extension("@rules_python//python/extensions:python.bzl", "python")
 python.toolchain(
     ignore_root_user_error = True,