Change log for ZSCALER_WEBPROXY

Date Changes
2025-06-13 - Fix the event timestamp format issue for the formats 'yyyy-MM-dd HH:mm:ss' and 'yyyy-MM-ddTHH:mm:ssZ'.
- Improved the parser performance to remove security_result.risk_score if pagerisk contains invalid values, as per the UDM documentation.
2025-05-30 - Added condition to handle timezone for `America/New York`.
2025-05-08 - Promoted ZSCALER_WEBPROXY Gold parser to default.
- This version includes many changes to improve the parser mappings (parser overhaul) - contact your Google representative to get a detailed list with all changes.
- This version will have an RC period - we encourage you to opt-in and make the required adjustments before it'll be automatically promoted to Default