Bump actions/checkout from 5 to 6

.github/workflows/build-book-pullrequest.yaml

@@ -38,7 +38,7 @@ jobs:
         shell: bash -l {0}
     steps:
       - name: checkout files in repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 2
       - name: Check Changes

.github/workflows/build-book.yaml

@@ -32,7 +32,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: checkout files in repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           fetch-depth: 2
       - name: Check Changes
@@ -88,7 +88,7 @@ jobs:
       run:
         shell: bash -l {0}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Build the book
         run: |
           # run notebooks

.github/workflows/deploy-preview.yaml

@@ -14,7 +14,7 @@ jobs:
       run:
         shell: bash -l {0}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Fetch Repo Name
         id: repo-name
         run: echo "::set-output name=value::$(echo '${{ github.repository }}' | awk -F '/' '{print $2}')"  # just the repo name, not owner

.github/workflows/link-checker.yaml

@@ -32,7 +32,7 @@ jobs:
   link-checker:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up Python
         uses: actions/setup-python@v6
         with:

.github/workflows/trigger-replace-links.yaml

@@ -10,7 +10,7 @@ jobs:
       contents: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Find and Replace Repository Name
         uses: jacobtomlinson/gha-find-replace@v3
         with: