Open links using the system default browser

[miguel-tadeu]

First, I'm very appreciated for this piece of software.

Is your feature request related to a problem? Please describe.
What happens is that I have a default browser, which I gladly use. When I click on any link in prospect-mail, it just opens Chrome. I would like to open in my default browser (or define the path for my browser)

Describe the solution you'd like
Check the system default browser and use it to open links.

Describe alternatives you've considered
As an alternative, allow to config the path for the browser binary.

Version in use
prospect-mail 0.5.1

Additional context
Not applied