fix keymaps

packages/core/src/extensions/keymap.ts

@@ -1,19 +0,0 @@
-import { keymap } from 'prosemirror-keymap'
-import { baseKeymap } from 'prosemirror-commands'
-import { undoInputRule } from 'prosemirror-inputrules'
-import { createExtension } from '../Extension'
-
-export const Keymap = createExtension({
-  addProseMirrorPlugins() {
-    return [
-      keymap({ Backspace: undoInputRule }),
-      keymap(baseKeymap),
-    ]
-  },
-})
-
-declare module '../Editor' {
-  interface AllExtensions {
-    Keymap: typeof Keymap,
-  }
-}