update triggers PHP-Warning in WP 5.5

[mcguffin]

Bug Report

• [x] Yes, I reviewed the contribution guidelines.
• [x] Yes, more specifically, I reviewed the guidelines on how to write clear bug reports.

Describe the current, buggy behavior

At any of these commands ...

wp language core update
wp language theme update --all
wp language plugin update --all

... a PHP-Warning is thrown:

PHP Warning:  Declaration of WP_CLI\LanguagePackUpgrader::download_package($package, $check_signatures = false) should be compatible with WP_Upgrader::download_package($package, $check_signatures = false, $hook_extra = Array) in phar:///home/swilkens/bin/wp/vendor/wp-cli/language-command/src/WP_CLI/LanguagePackUpgrader.php on line 51

Provide additional context/Screenshots

There is a similar issue in core command: https://github.com/wp-cli/core-command/issues/169

$ wp cli info
OS: Linux 3.10.0-[NOT_DISCLOSED] #1 SMP [NOT_DISCLOSED] UTC 2020 x86_64
Shell:  /bin/bash
PHP binary: /[NOT_DISCLOSED]/php
PHP version:    7.4.11
php.ini used:   /[NOT_DISCLOSED]/php.ini
WP-CLI root dir:    phar://wp-cli.phar/vendor/wp-cli/wp-cli
WP-CLI vendor dir:  phar://wp-cli.phar/vendor
WP_CLI phar path:   [NOT_DISCLOSED]
WP-CLI packages dir:    [NOT_DISCLOSED]
WP-CLI global config:   
WP-CLI project config:  
WP-CLI version: 2.4.0

$ wp core version --extra
WordPress version: 5.5.2
Database revision: 48748
TinyMCE version:   4.9100 (49100-20200624)
Package language:  de_DE

[wojsmol]

Hi This issue is already see https://github.com/wp-cli/language-command/pull/100. You can already test the fix with the WP-CLI nightly version, which you can use via wp cli update --nightly.

[strarsis]

+1, same issue with WP-CLI 2.4.0 which should be the latest one at time of writing. Has this fix been merged and released now?