build(deps): bump actions/checkout from 2 to 3 (jupyter-book#1658)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/pdf.yml

@@ -17,7 +17,7 @@ jobs:
         python-version: [3.8]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v3
       with:
@@ -51,7 +51,7 @@ jobs:
         python-version: [3.8]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v3
       with:

.github/workflows/tests.yml

@@ -14,7 +14,7 @@ jobs:
   pre-commit:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python 3.8
       uses: actions/setup-python@v3
       with:
@@ -24,7 +24,7 @@ jobs:
   pre-commit-hook:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python 3.8
       uses: actions/setup-python@v3
       with:
@@ -48,7 +48,7 @@ jobs:
         python-version: [3.8]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v3
       with:
@@ -102,7 +102,7 @@ jobs:
         sphinx: [">=3,<4", ">=4,<5"]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v3
       with:
@@ -134,7 +134,7 @@ jobs:
         python-version: [3.9]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v3
       with:
@@ -163,7 +163,7 @@ jobs:
         python-version: [3.9]
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v3
       with:
@@ -196,7 +196,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Set up Python 3.8
         uses: actions/setup-python@v3
         with: