Use node 18.x in continuous integration (#2819)

.github/workflows/e2e-test.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [18.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/generate-theme-doc.yml

@@ -12,7 +12,7 @@ jobs:
     name: Generate theme doc
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [18.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/preview-theme.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [18.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/stale-theme-pr-closer.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [18.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [18.x]
 
     steps:
       - uses: actions/checkout@v3

.github/workflows/update-langs.yaml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [16.x]
+        node-version: [18.x]
 
     steps:
       - uses: actions/checkout@v3