Replace deprecated Google Chart API for QR code generation

[ivanshyu]

Description

The qr_code_url method in GoogleAuthenticator struct is currently using the Google Chart API (https://chart.googleapis.com/chart) to generate QR codes. However, this API has been officially deprecated by Google and is no longer supported or maintained.

As per Google's announcement:

"The Image Charts API has been officially deprecated as of March 14, 2019 and turned down on March 14, 2023."

This means that the QR code generation functionality is now broken and needs to be updated to use an alternative method.

Current Implementation

authenticator.rs (lines 249-271)

    pub fn qr_code_url(
        &self,
        secret: &str,
        name: &str,
        title: &str,
        width: u32,
        height: u32,
        level: ErrorCorrectionLevel,
    ) -> String {
        let width = if width == 0 { 200 } else { width };
        let height = if height == 0 { 200 } else { height };

        // Scheme will be a url to the totp we will use. Since it is a query parameter of the final
        // url, it must be percent encoded. In turn, this means that `name` and `title` must be
        // percent encoded twice for the final url to work if they contain characters that are not
        // allowed in urls.
        let scheme = Self::create_scheme(name, secret, title);
        let scheme = utf8_percent_encode(&scheme, NON_ALPHANUMERIC);
        format!(
            "https://chart.googleapis.com/chart?chs={}x{}&chld={}|0&cht=qr&chl={}",
            width, height, level, scheme
        )
    }

Questions

• Instead of removing the qr_code_url method entirely, should we modify it to simply return the result of Self::create_scheme(name, secret, title)? This would provide users with the TOTP URI, but we'd lose the ability to specify height, width, and error correction level.

[camsjams]

Also it looks like https://quickchart.io/chart is mostly a drop in replacement for https://chart.googleapis.com/chart.

I did a replace on https://chart.googleapis.com/chart=>https://quickchart.io/chart in the generated URL and it works, mostly the same aside from slightly different formatting style.