klipper: 0.9.1 -> unstable-2021-01-31

Moving to unstable as it seems like they are back to not cutting
releases

pkgs/servers/klipper/default.nix

@@ -6,13 +6,13 @@
 }:
 stdenv.mkDerivation rec {
   name = "klipper";
-  version = "0.9.1";
+  version = "unstable-2021-01-31";
 
   src = fetchFromGitHub {
     owner = "KevinOConnor";
     repo = "klipper";
-    rev = "v${version}";
-    sha256 = "1wgklngsz6xxl25qxi9fkqhbyhwy61iyyk76ycq68b3miayrkgpj";
+    rev = "ef4d9c3abd30ae8a485020fd9ff2fb4529a143b3";
+    sha256 = "puAkSGL0DD0JUWejPdzr7zKIW2UP2soBBtgm2msUKzA=";
   };
 
   sourceRoot = "source/klippy";