update libreoffice impress example

desktop_env/evaluators/metrics/__init__.py

@@ -14,3 +14,4 @@ from .gimp import increase_saturation, decrease_brightness, check_file_exists, c
 from .general import check_csv, check_accessibility_tree, check_list, run_sqlite3
 from .thunderbird import check_thunderbird_prefs, check_thunderbird_filter
 from .vscode import compare_text_file, compare_config, compare_answer, is_extension_installed
+from .impress import check_slide_numbers_color, compare_pptx_files, check_for_two_lines