⬆️ Update actions/checkout requirement to v2.3.4

Updates the requirements on [actions/checkout](https://github.com/actions/checkout) to permit the latest version.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/commits/5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f)

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

Author: dependabot[bot]

.github/workflows/CI.yml

@@ -18,7 +18,7 @@ jobs:
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2.3.4
     - uses: UziTech/action-setup-atom@v1
       with:
         channel: ${{ matrix.channel }}
@@ -37,7 +37,7 @@ jobs:
     if: "!contains(github.event.head_commit.message, '[skip ci]')"
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2.3.4
       - uses: actions/setup-node@v1
         with:
           node-version: '12.x'
@@ -53,7 +53,7 @@ jobs:
       github.event.repository.fork == false
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2.3.4
       - uses: UziTech/action-setup-atom@v1
       - uses: actions/setup-node@v1
         with:

.github/workflows/codeql-analysis.yml

@@ -35,7 +35,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL