i18n: add missing translation keys (#7436)

## Summary

Adds i18n values for these missing keys:
6a73288ce3/src/components/dialog/content/MissingCoreNodesMessage.vue (L16-L29)

Fixes warning in console.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7436-i18n-add-missing-translation-keys-2c86d73d365081e49460dab121b86c2f)
by [Unito](https://www.unito.io)

src/locales/en/main.json

@@ -1560,6 +1560,11 @@
     "updateFrontend": "Update Frontend",
     "dismiss": "Dismiss"
   },
+  "loadWorkflowWarning": {
+    "outdatedVersion": "This workflow was created with a newer version of ComfyUI ({version}). Some nodes may not work correctly.",
+    "outdatedVersionGeneric": "This workflow was created with a newer version of ComfyUI. Some nodes may not work correctly.",
+    "coreNodesFromVersion": "Core nodes from version {version}:"
+  },
   "errorDialog": {
     "defaultTitle": "An error occurred",
     "loadWorkflowTitle": "Loading aborted due to error reloading workflow data",