Modernize actions

Author: timj

.github/workflows/build.yaml

@@ -16,13 +16,13 @@ jobs:
         python-version: ["3.11", "3.12", "3.13"]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           # Need to clone everything to determine version from git.
           fetch-depth: 0
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
           cache: "pip"
@@ -57,7 +57,7 @@ jobs:
           pytest -r a -v --cov=python --cov=tests --cov-report=xml --cov-report=term --cov-branch \
             --junitxml=junit.xml -o junit_family=legacy
       - name: Upload coverage to codecov
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v5
         with:
           files: ./coverage.xml
           token: ${{ secrets.CODECOV_TOKEN }}
@@ -74,15 +74,15 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/')
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           # Need to clone everything to embed the version.
           fetch-depth: 0
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
-          python-version: "3.11"
+          python-version: "3.13"
 
       - name: Install dependencies
         run: |

.github/workflows/build_docs.yaml

@@ -10,13 +10,13 @@ jobs:
   build_sphinx_docs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           # Need to clone everything for the git tags.
           fetch-depth: 0
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: '3.11'
           cache: "pip"

.github/workflows/do_not_merge.yaml

@@ -26,7 +26,7 @@ jobs:
             'DO NOT MERGE'. Remove this commit from the branch before merging
             or change the commit summary."
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Check requirements.txt for branches
         shell: bash

.github/workflows/docstyle.yaml

@@ -14,10 +14,10 @@ jobs:
   numpydoc:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
 
       - name: Install numpydoc
         run: |