Fix deprecated warning and update hugo version

1. Fix the warning like the follow:

    ERROR deprecated: site config key paginate was deprecated in
    Hugo v0.128.0 and will be removed in Hugo 0.141.0. Use
    pagination.pagerSize instead.

2. Update hugo in GitHub Action from 0.105.0 to 0.140.2

.github/workflows/hugo.yml

@@ -30,7 +30,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     env:
-      HUGO_VERSION: 0.105.0
+      HUGO_VERSION: 0.140.2
     steps:
       - name: Install Hugo CLI
         run: |

exampleSite/config.toml

@@ -3,9 +3,11 @@ theme = "hugo-theme-flat"
 themesDir = "../.."
 enableRobotsTXT = true
 hasCJKLanguage = true
-paginate = 4
 baseURL = ""
 
+[pagination]
+pagerSize = 4
+
 # these values are hugo built in markup config
 [markup.highlight]
 anchorLineNos = false