fix html file is not reported as UTF8 after conversion #404

Job	Run time
🎨 Linters	16s
⏪ Chardet Backward-Compatibility Test	1m 33s
✅ Tests (3.7)	23s
✅ Tests (3.8)	22s
✅ Tests (3.9)	27s
✅ Tests (3.10)	26s
✅ Tests (3.11)	23s
✅ Tests (3.12)	23s
📈 Detection Coverage	1m 17s
⚡ MypyC Tests (3.7, ubuntu-latest)	1m 58s
⚡ MypyC Tests (3.7, macos-latest)	6s
⚡ MypyC Tests (3.7, windows-latest)	3m 16s
⚡ MypyC Tests (3.8, ubuntu-latest)	1m 59s
⚡ MypyC Tests (3.8, macos-latest)	1m 54s
⚡ MypyC Tests (3.8, windows-latest)	3m 3s
⚡ MypyC Tests (3.9, ubuntu-latest)	1m 59s
⚡ MypyC Tests (3.9, macos-latest)	1m 28s
⚡ MypyC Tests (3.9, windows-latest)	2m 13s
⚡ MypyC Tests (3.10, ubuntu-latest)	1m 54s
⚡ MypyC Tests (3.10, macos-latest)	1m 22s
⚡ MypyC Tests (3.10, windows-latest)	2m 31s
⚡ MypyC Tests (3.11, ubuntu-latest)	1m 31s
⚡ MypyC Tests (3.11, macos-latest)	1m 8s
⚡ MypyC Tests (3.11, windows-latest)	2m 8s
⚡ MypyC Tests (3.12, ubuntu-latest)	1m 44s
⚡ MypyC Tests (3.12, macos-latest)	1m 7s
⚡ MypyC Tests (3.12, windows-latest)	2m 21s
⚡ Performance Test (no MypyC)	0s
	39m 12s

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