fix(deps): update msgpack for CVE-2026-54522 (#14898)

# Pull Request Template

## Description

This updates the locked `msgpack` gem from `1.8.0` to `1.8.3` so the
bundle-audit check no longer flags CVE-2026-54522. The upgrade stays
within the existing transitive dependency constraints used by `bootsnap`
and `datadog`.

Fixes:
https://app.circleci.com/pipelines/github/chatwoot/chatwoot/114757/workflows/f8c7b37f-27d5-45d4-9f1b-1d1782ebc4e3/jobs/162250

## Type of change

- [x] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

- `eval "$(rbenv init -)" && bundle exec bundle audit update && bundle
exec bundle audit check -v`
- `eval "$(rbenv init -)" && bundle exec rspec
spec/listeners/action_cable_listener_spec.rb`
- `eval "$(rbenv init -)" && RUBOCOP_CACHE_ROOT=tmp/rubocop_cache bundle
exec rubocop --no-server Gemfile`

## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

Gemfile.lock

@@ -570,7 +570,7 @@ GEM
     minitest (5.25.5)
     mock_redis (0.36.0)
       ruby2_keywords
-    msgpack (1.8.0)
+    msgpack (1.8.3)
     multi_json (1.15.0)
     multi_xml (0.9.1)
       bigdecimal (>= 3.1, < 5)