build(deps): bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/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)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/autopush.yml

@@ -10,7 +10,7 @@ jobs:
         if: startsWith(github.repository, 'inducer/')
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   run: |
                 curl -L -O https://tiker.net/ci-support-v0
                 . ./ci-support-v0

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
         name: Ruff
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: "Main Script"
             run: |
                 pipx install ruff
@@ -25,7 +25,7 @@ jobs:
     basedpyright:
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: "Main Script"
             run: |
                 curl -L -O https://tiker.net/ci-support-v0
@@ -39,14 +39,14 @@ jobs:
         name: Typos
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   uses: crate-ci/typos@master
 
     pytest3:
         name: Pytest on Py3
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: "Main Script"
             run: |
                 curl -L -O https://gitlab.tiker.net/inducer/ci-support/raw/main/build-and-test-py-project-within-miniconda.sh
@@ -56,7 +56,7 @@ jobs:
         name: Examples on Py3
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: "Main Script"
             run: |
                 curl -L -O https://tiker.net/ci-support-v0
@@ -80,7 +80,7 @@ jobs:
         name: Documentation
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: "Main Script"
             run: |
                 echo "- matplotlib" >> .test-conda-env-py3.yml
@@ -97,7 +97,7 @@ jobs:
         name: Tests for downstream project ${{ matrix.downstream_project }}
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v5
+        -   uses: actions/checkout@v6
         -   name: "Main Script"
             env:
                 DOWNSTREAM_PROJECT: ${{ matrix.downstream_project }}