Fix a few simple workflow lint errors (#17298)

* Use 'ubuntu-latest' instead of 'ubuntu-18.04' for longevity
* Update 'branches' configurations to be sequences as expected

Author: JamesMGreene

.github/workflows/autoupdate-branch.yml

@@ -7,7 +7,7 @@ jobs:
   autoupdate:
     if: github.repository == 'github/docs-internal' || github.repository == 'github/docs'
     name: autoupdate
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - uses: docker://chinthakagodawita/autoupdate-action:v1
         env:

.github/workflows/codeql.yml

@@ -2,9 +2,11 @@ name: CodeQL analysis
 
 on:
   push:
-    branches: main
+    branches:
+      - main
   pull_request:
-    branches: main
+    branches:
+      - main
     paths:
       - '**/*.js'
       - '.github/workflows/codeql.yml'