Update recommended docker container in README

[ksivaman]

Description

Update the recommended docker container in README from 25.01 (v1.14) to 25.03 (v2.1)

Type of change

• [x] Documentation change (change only to the documentation, either a fix or a new content)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Infra/Build change
• [ ] Code refactoring

Changes

• Update the recommended docker container in README from 25.01 (v1.14) to 25.03 (v2.1)

Checklist:

• [x] I have read and followed the contributing guidelines
• [x] The functionality is complete
• [ ] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes

[ptrendx]

Shouldn't we just wait a few days to do 25.04 instead?