Upgrade checkout action and add libreadline installation

Updated GitHub Actions workflow to use checkout@v6 and added installation of libreadline on Linux.

Author: FourierTransformer

.github/workflows/ci.yml

@@ -23,7 +23,14 @@ jobs:
     runs-on: ${{ matrix.runner }}
     steps:
       # Checks-out the repository under $GITHUB_WORKSPACE.
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
+      - name:  Install libreadline on linux
+        run:   |
+               if [ "$RUNNER_OS" == "Linux" ]; then
+                    sudo apt-get install -y libreadline-dev
+               fi
+        shell: bash
+
       - name: Install Lua (${{ matrix.lua }})
         run: |
           pip install git+https://github.com/luarocks/hererocks
@@ -50,10 +57,10 @@ jobs:
     runs-on: windows-2022
     steps:
       # Checks-out the repository under $GITHUB_WORKSPACE.
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Install Lua (${{ matrix.lua }})
         run: |
-          pip install git+https://github.com/luarocks/hererocks
+          pip install hererocks
           hererocks lua_install -r@28f9d98 --${{ matrix.lua }} --target ${{ matrix.target }}
       - name: Build lua-simdjson
         run: |