ci: use latest checkout action
diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index eb7005c..aaa8d92 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -12,7 +12,7 @@
     container:
       image: centos:7
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Install dependencies
       run: |
         curl -L -O https://github.com/Kitware/CMake/releases/download/v3.16.4/cmake-3.16.4-Linux-x86_64.sh
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index b8ea7d7..a22a9bb 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -11,7 +11,7 @@
     runs-on: macOS-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
 
     - name: Install dependencies
       run: brew install re2c p7zip cmake
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 7c856f3..d961582 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -11,7 +11,7 @@
     runs-on: windows-latest
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
 
     - name: Install dependencies
       run: choco install re2c