fix typo for machine

Author: mmcky

.github/workflows/linkcheck.yml

@@ -8,7 +8,7 @@ on:
 jobs:
   link-checking:
     name: Link Checking
-    runs-on: "ubunut-latest"
+    runs-on: "ubuntu-latest"
     permissions:
       issues: write # required for peter-evans/create-issue-from-file
     steps: