Add custom config file path support via -c flag

[ob7]

Optionally specify custom path to config.toml

Add ability to specify a custom configuration file path using the -c/--config flag
instead of always using the default ~/.config/tenere/config.toml path.

Changes:

• Add -c/--config CLI flag accepting a file path
• Modify Config::load() to handle custom config paths

Example usage:

tenere -c ~/path/to/custom/config.toml

[pythops]

Thanks for the PR 🙏
Looks nice yeah ! GJ 👏