Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

Author: dependabot[bot]

.github/workflows/autopush.yml

@@ -9,7 +9,7 @@ jobs:
         name: Automatic push to gitlab.tiker.net
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -   run: |
                 mkdir ~/.ssh && echo -e "Host gitlab.tiker.net\n\tStrictHostKeyChecking no\n" >> ~/.ssh/config
                 eval $(ssh-agent) && echo "$GITLAB_AUTOPUSH_KEY" | ssh-add -

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
         name: Flake8
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -
             uses: actions/setup-python@v5
             with:
@@ -31,7 +31,7 @@ jobs:
         name: Pylint
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -
             uses: actions/setup-python@v5
             with:
@@ -55,7 +55,7 @@ jobs:
             matrix:
                 python-version: ["3.8", "3.9", "3.x"]
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -
             uses: actions/setup-python@v5
             with:
@@ -77,7 +77,7 @@ jobs:
         name: Documentation
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -
             uses: actions/setup-python@v5
             with:
@@ -98,7 +98,7 @@ jobs:
         name: Tests for downstream project ${{ matrix.downstream_project }}
         runs-on: ubuntu-latest
         steps:
-        -   uses: actions/checkout@v3
+        -   uses: actions/checkout@v4
         -   name: "Main Script"
             env:
                 DOWNSTREAM_PROJECT: ${{ matrix.downstream_project }}