Update ci.yml

Author: pdimov

.github/workflows/ci.yml

@@ -40,7 +40,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Install packages
         if: matrix.install
@@ -126,7 +126,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Setup Boost
         shell: cmd