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/build.yml

@@ -28,7 +28,7 @@ jobs:
         & $env:PGBIN\psql --username=scheduler --host=localhost --list timetable
 
     - name: Check out code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Set up Golang
       uses: actions/setup-go@v4
@@ -75,7 +75,7 @@ jobs:
         PGPASSWORD=somestrong psql --username=scheduler --host=localhost --list timetable
 
     - name: Check out code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Set up Golang
       uses: actions/setup-go@v4
@@ -108,7 +108,7 @@ jobs:
         PGPASSWORD=somestrong psql --username=scheduler --host=localhost --list timetable
 
     - name: Check out code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Set up Golang
       uses: actions/setup-go@v4

.github/workflows/codeql-analysis.yml

@@ -39,7 +39,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

.github/workflows/docker.yml

@@ -19,7 +19,7 @@ jobs:
     steps:
 
     - name: Check out code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Set up Golang
       uses: actions/setup-go@v4

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
         go-version: '1.21'
 
     - name: Check out code into the Go module directory
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Unshallow
       run: git fetch --prune --unshallow
@@ -36,7 +36,7 @@ jobs:
     steps:
 
     - name: Check out code into the Go module directory
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Version strings
       id: version