Add documentation build job to CI workflow

Signed-off-by: Tsuyoshi Hombashi <[email protected]>

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
   build-package:
     runs-on: ubuntu-latest
     concurrency:
-      group: ${{ github.event_name }}-${{ github.workflow }}-${{ github.ref_name }}-build
+      group: ${{ github.event_name }}-${{ github.workflow }}-${{ github.ref_name }}-build-pkg
       cancel-in-progress: true
     timeout-minutes: 20
 
@@ -47,6 +47,32 @@ jobs:
           name: dist
           path: ./dist/*
 
+  build-docs:
+    runs-on: ubuntu-latest
+    concurrency:
+      group: ${{ github.event_name }}-${{ github.workflow }}-${{ github.ref_name }}-build-docs
+      cancel-in-progress: true
+    timeout-minutes: 20
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          fetch-tags: true
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          cache: pip
+          cache-dependency-path: |
+            setup.py
+            **/*requirements.txt
+            tox.ini
+
+      - run: make setup-ci
+
+      - run: make docs
+
   lint:
     runs-on: ubuntu-latest
     concurrency: