header.php: Update clipboard.js to v2.0.8 and add SRI hashes
header.php: Update clipboard.js to v2.0.8 and add SRI hashes

Signed-off-by: Aaron <d033e22ae348aeb5660fc2140aec35850c4da997@datahoarder.dev>
Flynntes/Sleeky,Flynntes/Sleeky,Flynntes/Sleeky