Merge pull request #9244 from scratchfoundation/renovate/scratch-paint-2.x

fix(deps): update dependency scratch-paint to v2.1.21

Author: renovate[bot]

package-lock.json

@@ -87,7 +87,7 @@
     "scratch-audio": "0.1.0-prerelease.20221123180128",
     "scratch-blocks": "0.2.0-prerelease.20231001225312",
     "scratch-l10n": "3.16.20231003032155",
-    "scratch-paint": "2.1.20",
+    "scratch-paint": "2.1.21",
     "scratch-render": "0.1.0-prerelease.20230913153807",
     "scratch-render-fonts": "1.0.0-prerelease.20221102164332",
     "scratch-storage": "2.2.1",