tests: improve the version string test
tests: improve the version string test

Use the recently introduced regex matching function to verify that
the version string has a correct format.

Signed-off-by: Bartosz Golaszewski <108de5fbc428215dc26df4468b48691526611148@gmail.com>

brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,brgl/libgpiod