This update adjusts the National Social Security Fund (NSSF) contribution limits to align with the latest regulations under the NSSF Act 2013. Specifically, the lower and upper earnings limits have been revised to reflect the 4th year of implementation, impacting the maximum combined contribution a worker can make. This ensures compliance with Kenyan tax laws.

This commit updates the NSSF Lower and Upper Earnings Limits in accordance with the 4th year of implementation of the NSSF Act 2013.

- Set Lower Earnings Limit (Tier 1) to 9,000.
- Set Upper Earnings Limit (Tier 2) to 108,000.
- Resulting max combined contribution is now 6,480.

Task: 5485002

Forward-Port-Of: odoo/enterprise#105019