[Gitleaks] Support configuration from pyproject.toml

**Is your feature request related to a problem? Please describe.** I'd love for `gitleaks` to support sourcing its configuration from a `[tool.gitleaks]` section of a `pyproject.toml` file. This would increase adoption of the tool in the Python ecosystem. **Describe the solution you'd like** I like tool-dedicated sections in `pyproject.toml` to keep the root of my repository clean. And review my tools configurations altogether in a centralized place. Because more often that not, I need to tweak the configuration of tools and coordinate them so they can play nice with each others. **Describe alternatives you've considered** Have a dedicated file in the root of my repository at `gitleaks.toml`. **Additional context** Here is a list of non-Python projects already supporting `pyproject.toml` file for configuration: - `[tool.ruff]`: https://docs.astral.sh/ruff/configuration/#configuring-ruff (Rust) - `[tool.typos]`: https://github.com/crate-ci/typos/blob/master/docs/reference.md (Rust) -