treewide: fix evaluation

cc @Mic92 @nixy @7c6f434c

pkgs/development/interpreters/hy/default.nix

···
     description = "A LISP dialect embedded in Python";
     homepage = http://hylang.org/;
     license = stdenv.lib.licenses.mit;
-    maintainers = stdenv.lib.maintainers.nixy; 
+    maintainers = [ stdenv.lib.maintainers.nixy ];
     platforms = stdenv.lib.platforms.all;
   };
 }

pkgs/development/python-modules/flask-wtf.nix

···
 
   meta = with stdenv.lib; {
     description = "Simple integration of Flask and WTForms.";
-    license = licenses.bsd;
+    license = licenses.bsd3;
     maintainers = [ maintainers.mic92 ];
     homepage = https://github.com/lepture/flask-wtf/;
   };

pkgs/development/python-modules/ghdiff.nix

···
 
   meta = with stdenv.lib; {
     homepage =  https://github.com/kilink/ghdiff;
-    license = license.mit;
+    license = licenses.mit;
     description = "Generate Github-style HTML for unified diffs.";
     maintainers = [ maintainers.mic92 ];
   };

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

···
     description = "a simple scripting language for Web browsing";
     license     = licenses.mit;
     platforms = platforms.all;
-    maintainers = with maintainers; [ Mic92 ];
+    maintainers = with maintainers; [ mic92 ];
   };
 }