Treewide: update some problematic homepages

These URLs are reported as problematic by Repology.
It could be a permanent redirection
or the page does not exist anymore

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

@@ -12,7 +12,7 @@ buildPythonPackage rec {
 
   meta = with stdenv.lib; {
     description = "Encoder/decoder and lint/validator for JSON (JavaScript Object Notation)";
-    homepage = http://deron.meranda.us/python/demjson/;
+    homepage = "https://github.com/dmeranda/demjson";
     license = licenses.lgpl3Plus;
     maintainers = with maintainers; [ bjornfor ];
     platforms = platforms.all;