update d/control: fix Lintian warning + update d/copyright (license link to https)

Hi, Dear Maintainer. I made some minor changes:

• update d/copyright (license link to https)

I checked the project with duck utility.

• update d/control: fix Lintian warning

W: telegram-desktop source: build-depends-on-obsolete-package Build-Depends-Arch: pkg-config => pkgconf
N: 
N:   The package build-depends on a package that has been superseded. If the
N:   superseded package is part of an ORed group, it should not be the first
N:   package in the group.
N: 
N:   Visibility: warning
N:   Show-Always: no
N:   Check: fields/package-relations
N: 

Also, I ran the lintian-brush utility.

Thank you!