remove unused tipatap palceholder extension

Author: ThieryMichel

examples/ra-offline/package.json

@@ -42,4 +42,4 @@
     "vite-plugin-pwa": "^1.2.0"
   },
   "name": "ra-offline"
-}
+}

packages/ra-input-rich-text/package.json

@@ -26,7 +26,6 @@
         "@tiptap/extension-color": "^3.20.4",
         "@tiptap/extension-highlight": "^3.20.4",
         "@tiptap/extension-image": "^3.20.4",
-        "@tiptap/extension-placeholder": "^3.20.4",
         "@tiptap/extension-text-align": "^3.20.4",
         "@tiptap/extension-text-style": "^3.20.4",
         "@tiptap/pm": "^3.20.4",

yarn.lock

@@ -6573,15 +6573,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@tiptap/extension-placeholder@npm:^3.20.4":
-  version: 3.20.4
-  resolution: "@tiptap/extension-placeholder@npm:3.20.4"
-  peerDependencies:
-    "@tiptap/extensions": ^3.20.4
-  checksum: d3d8b5a9d1e948db8c41a6377d94cfcfba6ddcb0027050fc5f206d289d5bcf01a2d614f29285bb0d0ec007ac8a3f84d6f1bce8976013c26fca8f91fb8d0b5e7f
-  languageName: node
-  linkType: hard
-
 "@tiptap/extension-strike@npm:^3.20.4":
   version: 3.20.4
   resolution: "@tiptap/extension-strike@npm:3.20.4"
@@ -20916,7 +20907,6 @@ __metadata:
     "@tiptap/extension-highlight": "npm:^3.20.4"
     "@tiptap/extension-image": "npm:^3.20.4"
     "@tiptap/extension-mention": "npm:^3.20.4"
-    "@tiptap/extension-placeholder": "npm:^3.20.4"
     "@tiptap/extension-text-align": "npm:^3.20.4"
     "@tiptap/extension-text-style": "npm:^3.20.4"
     "@tiptap/pm": "npm:^3.20.4"