0.3.9 - Updates and bugfixes

• Fix deprecated php warning on filter_input, using native WP functions for escaping & getting query var. Fixes another issue, where archived posts couldn't be trashed (Closes #35)
• Add aps_archived_label_string filter to modify the "Archived" string used for the status label throughout the plugin.
• Add aps_title_separator and aps_title_label to filter the post title separator and label. It defaults to 'Archived' with a : separator as a prefix to the content title. Disable the title label entirely by using add_filter( 'aps_title_prefix', '__return_false' ); in your functions.php file or custom plugin file. Closes #21
• Added aps_title_label_before filter, defaults to true - pass false to have the label appear after the title instead of before it, in which case it appears as "- Archived." This change along with the label string filter above closes #31
• Add PHPUnit tests & github actions.
• Update some comments and documentation, readmes, etc