v5.3.4 — the 5.3 line runs on PHP 7.4

Updated: se7enxweb/tagsbundle 5.3.4 runs on PHP 7.4 to 8.5 (^7.4 || ^8.0). The code is rewritten to PHP 7.4 syntax by Rector's PHP 7.4 downgrade set on top of the PHP 8.0 line (constructor promotion, match, nullsafe operator, union/mixed types, str_starts_with). It lints clean on PHP 7.4 and 8.5.

Verified: a fresh Exponential Platform Legacy 4.6.x install on PHP 7.4 with Composer 2.11.0-RC1 and security blocking on, using this release: composer install, the INSTALL.md steps for SQLite, all 18 page and sign-in checks, a legacy rich text publish; no CRITICAL log lines.