treewide: Change URLs to HTTPS

Lots of URLs were HTTP redirect to HTTPS. Changed those and checked them
if there's actual content. Inspired by
https://github.com/NixOS/nixpkgs/issues/60004

pkgs/development/python-modules/astropy/default.nix

@@ -22,7 +22,7 @@ buildPythonPackage rec {
 
   meta = {
     description = "Astronomy/Astrophysics library for Python";
-    homepage = http://www.astropy.org;
+    homepage = https://www.astropy.org;
     license = lib.licenses.bsd3;
     platforms = lib.platforms.all;
     maintainers = with lib.maintainers; [ kentjames ];