chore(deps): Bump the actions group across 1 directory with 4 updates

Bumps the actions group with 4 updates in the / directory: [actions/checkout](https://github.com/actions/checkout), [prefix-dev/setup-pixi](https://github.com/prefix-dev/setup-pixi), [actions/upload-artifact](https://github.com/actions/upload-artifact) and [actions/download-artifact](https://github.com/actions/download-artifact).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

Updates `prefix-dev/setup-pixi` from 0.9.1 to 0.9.3
- [Release notes](https://github.com/prefix-dev/setup-pixi/releases)
- [Commits](prefix-dev/setup-pixi@v0.9.1...v0.9.3)

Updates `actions/upload-artifact` from 4 to 5
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v5)

Updates `actions/download-artifact` from 5 to 6
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: prefix-dev/setup-pixi
  dependency-version: 0.9.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: actions
- dependency-name: actions/upload-artifact
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/cd.yml

@@ -19,45 +19,45 @@ jobs:
   build-book:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
-      - uses: prefix-dev/[email protected].1
+      - uses: prefix-dev/[email protected].3
         with:
           pixi-version: v0.28.2
 
       - name: Build the book
         run: pixi run book
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v5
         with:
           name: jupyterbook
           path: _build/html/*
 
   build-pyodide:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - uses: astral-sh/setup-uv@v7
 
       - name: Build the Pyodide output
         run: |
           uvx nox -s pyodide
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v5
         with:
           name: jupyterlite
           path: _output/*
 
   build-slides:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Make slides
         run: npx @marp-team/marp-cli@latest --input-dir slides --output _output
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v5
         with:
           name: slides
           path: _output/*
@@ -73,17 +73,17 @@ jobs:
       - name: Setup Pages
         uses: actions/configure-pages@v5
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: jupyterbook
           path: public
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: jupyterlite
           path: public/live
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: slides
           path: public/slides