Fix src/CalcGame.php, update text formatting

Author: prusov-code

src/CalcGame.php

@@ -28,7 +28,7 @@ function startCalcGame(): void
                 $expressionResult = $number1 * $number2;
                 break;
         }
-        $expression="{$number1}{$operation}{$number2}";
+        $expression="{$number1} {$operation} {$number2}";
         $questions[$i] = $expression ;
         $answers[$i] = $expressionResult;
     }