Implement changes from 2023 salary negotiations

This is a scheduled issue to implement changes arising from the 2023 pay negotiations.

Please note, whoever picks this issue up should create a copy of this issue for 2023 with a due date set to 2023-09-01

Technical Notes

The actual job requires that you add the figures from the All Grades (Excel) spreadsheet on the HR salary scales page to the module's salary_scales.yaml file.

Please remember to add a version tag to your commit and then raise MRs on the webapp and salaries-commitments projects to deploy the resulting changes. Link the MR's to this issue.