Allow decrement to work with negative numbers

Author: AydinHassan

src/Input/Number.php

@@ -92,7 +92,7 @@ public function ask() : InputResult
 
     public function validate(string $input) : bool
     {
-        return (bool) preg_match('/^\d+$/', $input);
+        return (bool) preg_match('/^-?\d+$/', $input);
     }
 
     public function filter(string $value) : string

test/Input/NumberTest.php

@@ -80,6 +80,11 @@ public function validateProvider() : array
             ['0', true],
             ['0000000000', true],
             ['9999999999', true],
+            ['-9999999999', true],
+            ['-54', true],
+            ['-1', true],
+            ['-t10', false],
+            ['-t', false],
         ];
     }