Error Array and string offset access syntax with curly braces is deprecated when installing fastadmin

An error occurred during fastadmin installation

Array and string offset access syntax with curly braces is deprecated

Chinese meaning: array and string offset access syntax with curly braces is deprecated

My PHP environment is caused by PHP 7.4 or PHP 8.0+

/thinkphp/library/think/db/Query.php in the root directory of fastadmin

400 lines

source code:

$seq = (ord($value{0}) % $rule['num']) + 1;

after modification

$seq = (ord($value[0]) % $rule['num']) + 1;