Fix nix direnv (#3613)

* Add kguiaddons to shell.nix

This package is needed to compile flameshot with USE_WAYLAND_CLIPBOARD

* Add .direnv to gitignore

This directory is automatically created by direnv when evaluating the
.envrc file

---------

Co-authored-by: mae <git@badat.dev>

.gitignore

@@ -75,3 +75,4 @@ data/flatpak/.flatpak-builder
 
 # Miscellaneous
 !docs/dev/Makefile
+.direnv

shell.nix

@@ -7,5 +7,5 @@ pkgs.mkShell {
     qt5.qttools
     qt5.qtsvg
   ];
-  buildInputs = [ pkgs.qt5.qtbase ];
+  buildInputs = with pkgs; [ qt5.qtbase libsForQt5.kguiaddons ];
 }