Add libfl-dev for CodeQL CI job

Author: mmicko

.github/workflows/codeql.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Install deps
-      run: sudo apt-get install bison flex libreadline-dev tcl-dev libffi-dev
+      run: sudo apt-get install bison flex libfl-dev libreadline-dev tcl-dev libffi-dev
 
     - name: Checkout repository
       uses: actions/checkout@v4