Fix file descriptor error for linux
Fixes: #1842 (closed)
browse_to() in the
obtain-secrets script should open up the Gitlab link in the browser, but it can't find the file descriptor on Linux as the Linux equivalent to OS X'
That's why I added a check whether
xdg-open exists on the system and if yes, run
xdg-open to open up the Gitlab tab in the system browser.