fix: bump redis-client to 0.26.4 to fix Sentinel resolution (#13689)

Description:
  ## Summary

- `redis-client` 0.22.2 uses `.call()` during Sentinel master
resolution, but `redis-rb` 5.x undefines `.call()` (only `.call_v()`
  exists), causing Sentinel connections to fail.
- Bumps `redis-client` from 0.22.2 to 0.26.4 which includes the upstream
fix (redis-rb/redis-client#283).
- Also bumps transitive dependency `connection_pool` from 2.5.3 to
2.5.5.

  Fixes #11665 https://github.com/chatwoot/chatwoot/issues/8368

  ## Test

  - `bundle exec rspec spec/lib/redis/config_spec.rb` passes
  - Full CI suite passes

Gemfile.lock

@@ -191,7 +191,7 @@ GEM
     coderay (1.1.3)
     commonmarker (0.23.10)
     concurrent-ruby (1.3.5)
-    connection_pool (2.5.3)
+    connection_pool (2.5.5)
     crack (1.0.0)
       bigdecimal
       rexml
@@ -736,7 +736,7 @@ GEM
       ffi (~> 1.0)
     redis (5.0.6)
       redis-client (>= 0.9.0)
-    redis-client (0.22.2)
+    redis-client (0.26.4)
       connection_pool
     redis-namespace (1.10.0)
       redis (>= 4)