Bump actions/checkout from 2 to 3 (#802)

Author: dependabot[bot]

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install dependencies (Linux)
         if: runner.os == 'Linux'

.github/workflows/codeql.yml

@@ -12,7 +12,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install dependencies
         run: sudo apt-get install z3 re2c ninja-build g++-10