feat: Colorful calendar output

[nothingelsematters]

This pull request brings colors for the calendar output.

Preview

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Explanation

This was achieved by collecting the colors using the regex to extract the information from style: these lines. Then using the proper colors with ANSI escape codes. It replaces only the colors it has found, therefore nothing will break if the format is changed, it will just fall back to the default color.

However, html2text was throwing errors on ANSI escape symbol \u{1b}, that is why this function is a workaround: it uses html2text on everything but this special character.