fix permissions for apt version pinning files

[ltalirz]

Permissions of the pin files were left unspecified, resulting in 0600 in my test case, which is not recommended (and caused e.g. the check_apt binary of icinga to fail when not run as root).

[ltalirz]

@josegonzalez By the way, I still can't merge without a review (and I don't have permissions to change the settings to exclude administrators).

That's fine with me - just to explain why you'll get a couple of review requests ;-)

[josegonzalez]

@ltalirz added you as a maintainer

[ltalirz]

Thanks, but I still see this when I click on "settings":

[ltalirz]

I.e. I cannot change the branch protection rules and without your review I cannot merge this

[josegonzalez]

Try now?

[ltalirz]

Thanks, now it works!