Fix missing prefix in _print_Allocate in FCodePrinter (pyccel#2092)

Add missing call and make string into f-string to fix pyccel#2091

Author: jalalium

pyccel/codegen/printing/fcode.py

@@ -2156,7 +2156,7 @@ def _print_Allocate(self, expr):
             elif expr.alloc_type == 'reserve':
                 var_code = self._print(expr.variable)
                 size_code = self._print(expr.shape[0])
-                return '{var_code} % reserve({size_code})\n'
+                return f'call {var_code} % reserve({size_code})\n'
             else:
                 return ''
         elif isinstance(class_type, (HomogeneousContainerType, DictType)):