[FSSDK-12521] chore: preparing for release v5.5.0 (#508)

* [FSSDK-12521] chore: preparing for release v5.5.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: remove internal tooling entries from changelog

Removed ruff linter migration and Arnica code risk warning entries
from the v5.5.0 changelog as they are internal CI/tooling changes
not relevant to SDK users.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Update CHANGELOG.md

Co-authored-by: Muzahidul Islam <129880873+muzahidul-opti@users.noreply.github.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Muzahidul Islam <129880873+muzahidul-opti@users.noreply.github.com>

Author: 3 people

CHANGELOG.md

@@ -1,5 +1,33 @@
 # Optimizely Python SDK Changelog
 
+## 5.5.0
+April 30th, 2026
+
+### New Features
+
+#### **Feature Rollout Support**
+
+- Added support for Feature Rollouts, a new rule type that combines Targeted Delivery simplicity with A/B test measurement capabilities. During project config parsing, the "everyone else" variation from the flag's rollout is automatically injected into feature rollout experiments, enabling correct evaluation without changes to decision logic. ([#499](https://github.com/optimizely/python-sdk/pull/499))
+- Removed experiment type validation from config parsing to support flexible rule types. ([#500](https://github.com/optimizely/python-sdk/pull/500))
+
+---
+
+### Enhancements
+
+- Added event retry support for reliable event dispatching. ([#475](https://github.com/optimizely/python-sdk/pull/475))
+- Excluded CMAB experiments from UserProfileService to prevent stale cached decisions. ([#474](https://github.com/optimizely/python-sdk/pull/474))
+- Cleaned up flag-level holdout fields for simplified configuration. ([#507](https://github.com/optimizely/python-sdk/pull/507))
+
+---
+
+### Bug Fixes
+
+- Fixed `return` in `finally` block silently swallowing exceptions. ([#505](https://github.com/optimizely/python-sdk/pull/505))
+- Fixed `PollingConfigManager` rejecting valid URL-only configuration. ([#497](https://github.com/optimizely/python-sdk/pull/497))
+
+---
+
+
 ## 5.4.0
 December 19th, 2025
 

optimizely/version.py

@@ -11,5 +11,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-version_info = (5, 4, 0)
+version_info = (5, 5, 0)
 __version__ = '.'.join(str(v) for v in version_info)