Add Next LS installation to CI workflow

- Install Next LS v0.23.3 binary for all platforms (Linux, macOS, Windows)
- Download platform-specific binaries from GitHub releases
- Add binaries to PATH for use in Elixir language server tests
- Ensures Next LS is available for optimal Elixir test performance
- Resolves CI dependency requirements for Elixir language server integration

.github/workflows/pytest.yml

@@ -40,6 +40,25 @@ jobs:
         with:
           elixir-version: '1.18.4'
           otp-version: '26.1'
+      - name: Install Next LS
+        run: |
+          if [[ "$RUNNER_OS" == "Linux" ]]; then
+            NEXT_LS_URL="https://github.com/elixir-tools/next-ls/releases/download/v0.23.3/next_ls_linux_amd64"
+            curl -fLo next-ls "$NEXT_LS_URL"
+          elif [[ "$RUNNER_OS" == "macOS" ]]; then
+            NEXT_LS_URL="https://github.com/elixir-tools/next-ls/releases/download/v0.23.3/next_ls_darwin_amd64"
+            curl -fLo next-ls "$NEXT_LS_URL"
+          elif [[ "$RUNNER_OS" == "Windows" ]]; then
+            NEXT_LS_URL="https://github.com/elixir-tools/next-ls/releases/download/v0.23.3/next_ls_windows_amd64.exe"
+            curl -fLo next-ls.exe "$NEXT_LS_URL"
+          fi
+          chmod +x next-ls* || true
+          # Add to PATH for the current step and future steps
+          if [[ "$RUNNER_OS" == "Windows" ]]; then
+            echo "$PWD" >> $GITHUB_PATH
+          else
+            echo "$PWD" >> $GITHUB_PATH
+          fi
       - name: Prepare java
         uses: actions/setup-java@v3
         with: