Run linter using PHP 8.1 as well (and fix any issues)

[macbre]

Production (when switched to PHP 8.1) reports:

$ cat phperror.log | grep 22-Sep | cut -d] -f2 | sort | uniq
 PHP Deprecated:  Implicit conversion from float 3.5 to int loses precision in /usr/home/macbre/elecena/git/app/controllers/search/SearchController.class.php on line 438
 PHP Deprecated:  Implicit conversion from float 7.5 to int loses precision in /usr/home/macbre/elecena/git/app/controllers/parameters/ParametersController.class.php on line 300
 PHP Deprecated:  Implicit conversion from float 7.5 to int loses precision in /usr/home/macbre/elecena/git/app/controllers/search/SearchController.class.php on line 438
 PHP Deprecated:  Return type of DatabaseResult::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange
 PHP Deprecated:  Return type of DatabaseResult::current() should either be compatible with Iterator::current(): mixed, or the #[\ReturnTypeWillChange
 PHP Deprecated:  Return type of DatabaseResult::key() should either be compatible with Iterator::key(): mixed, or the #[\ReturnTypeWillChange
 PHP Deprecated:  Return type of DatabaseResult::next() should either be compatible with Iterator::next(): void, or the #[\ReturnTypeWillChange
 PHP Deprecated:  Return type of DatabaseResult::rewind() should either be compatible with Iterator::rewind(): void, or the #[\ReturnTypeWillChange
 PHP Deprecated:  Return type of DatabaseResult::valid() should either be compatible with Iterator::valid(): bool, or the #[\ReturnTypeWillChange
 PHP Deprecated:  Return type of Predis\Client::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange
 PHP Deprecated:  trim(): Passing null to parameter #1 ($string) of type string is deprecated in /usr/home/macbre/elecena/git/app/vendor/elecena/nano/classes/Router.class.php on line 286
 PHP Notice:  ob_end_clean(): Failed to discard buffer of zlib output compression (2) in /usr/home/macbre/elecena/git/app/vendor/elecena/nano/classes/Response.class.php on line 365

[macbre]

Yay!

 ------ ----------------------------------------------------------------------- 
  Line   classes/DatabaseResult.class.php                                       
 ------ ----------------------------------------------------------------------- 
  84     Return type mixed of method DatabaseResult::count() is not covariant   
         with tentative return type int of method Countable::count().           
         💡 Make it covariant, or use the #[\ReturnTypeWillChange] attribute    
         to temporarily suppress the error.                                     
  92     Return type mixed of method DatabaseResult::rewind() is not covariant  
         with tentative return type void of method Iterator::rewind().          
         💡 Make it covariant, or use the #[\ReturnTypeWillChange] attribute    
         to temporarily suppress the error.                                     
  101    Return type mixed of method DatabaseResult::current() is not           
         covariant with tentative return type mixed of method                   
         Iterator::current().                                                   
         💡 Make it covariant, or use the #[\ReturnTypeWillChange] attribute    
         to temporarily suppress the error.                                     
  110    Return type mixed of method DatabaseResult::key() is not covariant     
         with tentative return type mixed of method Iterator::key().            
         💡 Make it covariant, or use the #[\ReturnTypeWillChange] attribute    
         to temporarily suppress the error.                                     
  115    Return type mixed of method DatabaseResult::next() is not covariant    
         with tentative return type void of method Iterator::next().            
         💡 Make it covariant, or use the #[\ReturnTypeWillChange] attribute    
         to temporarily suppress the error.                                     
  122    Return type mixed of method DatabaseResult::valid() is not covariant   
         with tentative return type bool of method Iterator::valid().           
         💡 Make it covariant, or use the #[\ReturnTypeWillChange] attribute    
         to temporarily suppress the error.                                     
 ------ ----------------------------------------------------------------------- 
Error:  [ERROR] Found 6 errors