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/pytz/default.nix

@@ -15,7 +15,7 @@ buildPythonPackage rec {
 
   meta = with lib; {
     description = "World timezone definitions, modern and historical";
-    homepage = "http://pythonhosted.org/pytz";
+    homepage = "https://pythonhosted.org/pytz";
     license = licenses.mit;
     maintainers = with maintainers; [ dotlambda ];
   };