Add GHA for rendering the book

.Rbuildignore

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+^\.github$

.github/.gitignore

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+*.html

.github/dependabot.yaml

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+version: 2
+
+updates:
+  # Keep dependencies for GitHub Actions up-to-date
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/bookdown.yaml

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+# Workflow derived from https://github.com/r-lib/actions/tree/v2/examples
+# Need help debugging build failures? Start at https://github.com/r-lib/actions#where-to-find-help
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+    branches: [main, master]
+  schedule:
+    # * is a special character in YAML so you have to quote this string
+    # Trigger once a week, on a Sunday (0)
+    - cron: "0 0 * * 0"
+  workflow_dispatch:
+
+name: bookdown
+
+jobs:
+  bookdown:
+    runs-on: ubuntu-latest
+    # Only restrict concurrency for non-PR jobs
+    concurrency:
+      group: pkgdown-${{ github.event_name != 'pull_request' || github.run_id }}
+    env:
+      GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: r-lib/actions/setup-pandoc@v2
+        with:
+          pandoc-version: "3.1.8"
+
+      - uses: r-lib/actions/setup-r@v2
+        with:
+          use-public-rspm: true
+
+      - uses: r-lib/actions/setup-renv@v2
+
+      - name: Cache bookdown results
+        uses: actions/cache@v3
+        with:
+          path: _bookdown_files
+          key: bookdown-${{ hashFiles('**/*Rmd') }}
+          restore-keys: bookdown-
+
+      - name: Build site
+        run: bookdown::render_book("index.Rmd", quiet = TRUE)
+        shell: Rscript {0}
+
+      - name: Deploy to GitHub pages 🚀
+        if: github.event_name != 'pull_request'
+        uses: JamesIves/github-pages-deploy-action@v4.4.1
+        with:
+          branch: gh-pages
+          folder: _book