chore: Update actions/checkout version to v4 (axel-op#31)

* chore(docs): Update `actions/checkout`'s version to `v4` in the example.

* Bump `actions/checkout` to `v4`

Author: kyu08

.github/workflows/codeql-analysis.yml

@@ -33,7 +33,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

.github/workflows/compile.yml

@@ -8,7 +8,7 @@ jobs:
   compile-and-push:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-node@v3
         with:
           node-version: 16

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
         version: ["1.6", ""]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-java@v1
         with:
           java-version: ${{ matrix.java-version }}
@@ -37,7 +37,7 @@ jobs:
         version: ["1.6", ""]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-java@v1
         with:
           java-version: ${{ matrix.java-version }}

.github/workflows/validate-action-typings.yml

@@ -6,5 +6,5 @@ jobs:
   validate-typings:
     runs-on: "ubuntu-latest"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: krzema12/github-actions-typing@v0

README.md

@@ -24,7 +24,7 @@ jobs:
   formatting:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3 # v2 minimum required
+      - uses: actions/checkout@v4 # v2 minimum required
       - uses: axel-op/googlejavaformat-action@v3
         with:
           args: "--skip-sorting-imports --replace"
@@ -44,7 +44,7 @@ jobs:
   formatting:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3 # v2 minimum required
+      - uses: actions/checkout@v4 # v2 minimum required
       - uses: axel-op/googlejavaformat-action@v3
         with:
           args: "--set-exit-if-changed"
@@ -62,7 +62,7 @@ jobs:
   formatting:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3 # v2 minimum required
+      - uses: actions/checkout@v4 # v2 minimum required
       - uses: axel-op/googlejavaformat-action@v3
         with:
           args: "--replace"