fix: memory leaks and invalid CSS in WebVTT encoder#2164

cfsmp3 merged 2 commits intoCCExtractor:masterCCExtractor/ccextractor:masterfrom

Varadraj75:fix/webvtt-memory-leaks-and-cssVaradraj75/ccextractor:fix/webvtt-memory-leaks-and-cssCopy head branch name to clipboard