fix: update license information in README and pyproject.toml

[lsvishaal]

Fix broken LICENSE link on PyPI package page by updating both README and pyproject.toml files.

• Add license field to pyproject.toml for proper PyPI display
• Fix relative LICENSE link in README to absolute GitHub URL

Fixes #3326

Description

The PyPI package page at https://pypi.org/project/mem0ai/ displays the README.md content, but the relative LICENSE link [LICENSE](LICENSE) becomes broken (404 error). This fix addresses the issue by:

1. Adding proper license metadata to pyproject.toml using PEP 639 standard
2. Converting the relative LICENSE link to an absolute GitHub URL

Type of change

• Bug fix (non-breaking change which fixes an issue)
• Documentation update

How Has This Been Tested?

Verification performed:

• Confirmed LICENSE file exists at repository root
• Verified GitHub LICENSE URL is accessible and points to correct file
• Validated pyproject.toml syntax follows PEP 639 standard
• Checked that license metadata format is compatible with PyPI display

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have checked my code and corrected any misspellings

Maintainer Checklist

• closes DOC: LICENSE link on https://pypi.org/project/mem0ai/ is invalid #3326

[parshvadaftari]

@lsvishaal Thanks a lot for fixing the issue and contributing to mem0 🚀

[lsvishaal]

@deshraj
@parshvadaftari

Thank you for approval and merge! this was my first PR + merge! 😁