⬇️(frontend) downgraded blocknote to 0.21.0

The last version of Blocknote (0.22.0) has a bug,
when we copy paste a title, the app sometimes crashes.
Better to downgrade to 0.21.0 until the bug is fixed.

src/frontend/apps/impress/package.json

@@ -15,9 +15,9 @@
     "test:watch": "jest --watch"
   },
   "dependencies": {
-    "@blocknote/core": "0.22.0",
-    "@blocknote/mantine": "0.22.0",
-    "@blocknote/react": "0.22.0",
+    "@blocknote/core": "0.21.0",
+    "@blocknote/mantine": "0.21.0",
+    "@blocknote/react": "0.21.0",
     "@gouvfr-lasuite/integration": "1.0.2",
     "@hocuspocus/provider": "2.15.0",
     "@openfun/cunningham-react": "2.9.4",