Correct singularization of mas

Author: vdauchy

src/Rules/French/Uninflected.php

@@ -14,6 +14,7 @@ public static function getSingular(): iterable
         yield from self::getDefault();
 
         yield new Pattern('bois');
+        yield new Pattern('mas');
     }
 
     /** @return Pattern[] */

tests/Rules/French/FrenchFunctionalTest.php

@@ -56,6 +56,7 @@ public function dataSampleWords(): array
             ['festival', 'festivals'],
             ['récital', 'récitals'],
             ['bois', 'bois'],
+            ['mas', 'mas'],
         ];
     }