fix: format by pyink on database_session_service.py

[anencore94]

Fix failed pyink format on current main branch by uv run pyink --config pyproject.toml ./src

[hangfei]

we are using two-space. is there special rule for this case?

[anencore94]

we are using two-space. is there special rule for this case?

Thx for your reply :) @hangfei
I'm not sure what is the intended convention, but as following from the CONTRIBUTING.md, pyink automaticallly format that file as four spaces for ValueError wrapping.

Maybe it depends on the version of pyink or python? if it doesn't raise an issue in workflow?

However, as I see the other code lines, use four spaces when we raise some Error class