Support for psr/log:^2.0

However, I just pulled down the codeigniter4/framework repo down locally to check it out and found something I didn't expect.  It appears Codeigniter4 actually overrides psr/log with it's own copy located in system/ThirdParty/PSR/Log via the AutoloadConfig class (system/Config/AutoloadConfig.php).  It appears to be a copy of psr/log 3.0 in v4.5.0, and psr/log 1.X in v4.4.8, which makes sense, based off the requirement in composer.json.  Based on the comments, it looks like this was done for a slight autoloading performance enhancement for these frequently used classes.

Slightly different. "system/ThirdParty/PSR/Log" is used only when Composer is not used.
Remember CodeIgniter4 still supports Zip installations, and it depends on psr/log.
So we need the copy for Zip installations.

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