fix(ci): install libegl1 on Ubuntu and normalize line endings in epub test

- Add system dependency step for libegl1 to fix PyQt6 import on headless CI
- Normalize CRLF to LF in epub exporter whitespace test for Windows CI

.github/workflows/test_pip.yml

@@ -30,6 +30,10 @@ jobs:
         uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
+      - name: Install system dependencies (Ubuntu)
+        if: runner.os == 'Linux'
+        run: sudo apt-get update && sudo apt-get install -y libegl1
+
 
       - name: Cache pip
         uses: actions/cache@v6