git-cola: update dependencies and make it work in darwin

- `pyinotify` was removed a long time ago:
https://github.com/git-cola/git-cola/pull/510
- `sip_4` does not seem to be needed, at least there is no mention at docs
  and the program seems to works fine without it
- `send2trash` added since it is an optional feature:
https://github.com/git-cola/git-cola#optional-features

The removal of `pyinotify` also makes this build and works in darwin, so
removing the `meta.platforms` (will inherit from `buildPythonApplication`
instead).

pkgs/applications/version-management/git-cola/default.nix

@@ -1,9 +1,6 @@
 { lib, fetchFromGitHub, python3Packages, gettext, git, qt5 }:
 
-let
-  inherit (python3Packages) buildPythonApplication pyqt5 sip_4 pyinotify qtpy;
-
-in buildPythonApplication rec {
+python3Packages.buildPythonApplication rec {
   pname = "git-cola";
   version = "4.1.0";
 
@@ -15,7 +12,7 @@ in buildPythonApplication rec {
   };
 
   buildInputs = [ git gettext ];
-  propagatedBuildInputs = [ pyqt5 sip_4 pyinotify qtpy ];
+  propagatedBuildInputs = with python3Packages; [ pyqt5 qtpy send2trash ];
   nativeBuildInputs = [ qt5.wrapQtAppsHook ];
 
   doCheck = false;
@@ -28,7 +25,6 @@ in buildPythonApplication rec {
     homepage = "https://github.com/git-cola/git-cola";
     description = "A sleek and powerful Git GUI";
     license = licenses.gpl2;
-    platforms = platforms.linux;
     maintainers = [ maintainers.bobvanderlinden ];
   };
 }