Support python 3.13

- Update folder `eng`: for any place which uses python 3.12, we shall update to use python 3.13
- Update file `**/requirements.txt`: update `azure-core` version to `1.35.0` and `azure-mgmt-core` to `1.6.0`
- Update file `**/tox.ini`: update `py312` to `py313` for `envlist`