Keep dependency versions in sync for WORKSPACE and MODULE.bazel

As mentioned in the Bazel blog article, the old `WORKSPACE` system is
planned to be disabled by default in Bazel 8, and to be removed
altogether in Bazel 9.  The `WORKSPACE` file will eventually be removed,
but for now, it’s best to keep the dependency versions in both systems
in sync, so that we can build the project with Bzlmod either disabled or
enabled.

Note that there is an issue that prevents this project from depending on
protobuf v22 and higher.  Until that issue is fixed, v21.7 is the
highest version that both systems have in common.

References:

- https://blog.bazel.build/2023/12/11/bazel-7-release.html#bzlmod
- #186

MODULE.bazel

@@ -1,4 +1,4 @@
 module(name = "protobuf_javascript", version = "3.21.2")
 
 bazel_dep(name = "protobuf", version = "21.7", repo_name = "com_google_protobuf")
-bazel_dep(name = "rules_pkg", version = "0.9.1")
+bazel_dep(name = "rules_pkg", version = "0.7.0")

WORKSPACE

@@ -4,8 +4,9 @@ load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 http_archive(
  name = "com_google_protobuf",
- strip_prefix = "protobuf-21.3",
- urls = ["https://github.com/protocolbuffers/protobuf/archive/refs/tags/v21.3.zip"],
+ urls = ["https://github.com/protocolbuffers/protobuf/archive/refs/tags/v21.7.zip"],
+ sha256 = "e13ca6c2f1522924b8482f3b3a482427d0589ff8ea251088f7e39f4713236053",
+ strip_prefix = "protobuf-21.7",
 )
 
 load("@com_google_protobuf//:protobuf_deps.bzl", "protobuf_deps")