fix: Remove useless use statement

[tintou]

PHP is warning that "The use statement with non-compound name 'CurlHandle' has no effect". This makes the web updater fail to update when the warning is propagated.
Closes: #687

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[skjnldsv]

@tintou could you address the failing check ? :)
https://github.com/nextcloud/updater#developmentmaking-changes

[tintou]

@skjnldsv It's not clear to me how to address this, I tried composer install, make updater.phar and make index.php with no luck
Edit: okay I had to update composer to the latest version
Edit2: it's still not that, I don't know

[Altahrim]

Hello @tintou,

Thank you for taking care of this.
There is also an error with Closure, but hidden by the header.
I am trying a different approach here as CLI updater doesn't have the issue: #703