Fix Composer 2 compatibility

[brandonkelly]

When installing this plugin with Composer 1, the following deprecation notice is output:

Deprecation Notice: Class bolden\htmlcache\records\HtmlCacheCache located in ./vendor/bolden/htmlcache/src/records/HtmlCacheCachesRecord.php does not comply with psr-4 autoloading standard. It will not autoload anymore in Composer v2.0.

Composer 2 was released on October 24, and is now the default version that will be installed, so it’s critical that this gets resolved ASAP, or people will start getting Class not found errors.

To fix, run the following command:

> git mv src/records/HtmlCacheCachesRecord.php src/records/HtmlCacheCache.php

Then commit your change and tag a new release.

(Note that you must use the git mv command, as Git tends to not notice case-sensitive file renames otherwise.)