ci: bump actions/checkout from 2.3.5 to 2.4.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.5 to 2.4.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2.3.5...v2.4.0)

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

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

.github/workflows/codeql-analysis.yml

@@ -10,7 +10,7 @@ jobs:
   CodeQL-Build:
     runs-on: ubuntu-18.04
     steps:
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
 
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v1

.github/workflows/release.yml

@@ -9,7 +9,7 @@ jobs:
   release:
     runs-on: ubuntu-18.04
     steps:
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
 
       - name: Dump GitHub context
         env:

.github/workflows/test-action.yml

@@ -19,7 +19,7 @@ jobs:
           - 'latest'
           - '0.4.0'
     steps:
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
 
       - name: Setup mdBook
         uses: peaceiris/actions-mdbook@v1.1.14

.github/workflows/test.yml

@@ -21,7 +21,7 @@ jobs:
           - 'macos-latest'
           - 'windows-latest'
     steps:
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
 
       - name: Read .nvmrc
         run: echo "::set-output name=NVMRC::$(cat .nvmrc)"

.github/workflows/update-major-tag.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-20.04
     timeout-minutes: 1
     steps:
-      - uses: actions/checkout@v2.3.5
+      - uses: actions/checkout@v2.4.0
 
       - name: Update major tag
         run: |