fix deployment (#3)

flet <= 0.9.0

remove snackbar `open=True`

remove if __name__ == "__main__"

update manifest.json

update index.html

change view for web deploy success

remove icon flag

update README.md

update appveyor.yml

update appveyor.yml

cleaned and optimized code | introduced NavigationBar

update requirements.txt

cleaned and optimized code

Create index.html