testing/php8-pecl-csv: fix name to lowercase for .ini
Quick fix for
PHP Warning: PHP Startup: Unable to load dynamic library 'CSV' (tried: /usr/lib/php8/modules/CSV (Error loading shared library /usr/lib/php8/modules/CSV: No such file or directory), /usr/lib/php8/modules/CSV.so (Error loading shared library /usr/lib/php8/modules/CSV.so: No such file or directory)) in Unknown on line 0