fix: tests

Author: BobTheBuidler

mypyc/test-data/fixtures/ir.py

@@ -174,8 +174,8 @@ def __getitem__(self, i: slice) -> bytes: ...
     def join(self, x: Iterable[object]) -> bytes: ...
     def decode(self, encoding: str=..., errors: str=...) -> str: ...
     def __iter__(self) -> Iterator[int]: ...
-    def ljust(self, width: int, fillchar: bytes) -> bytes: ...
-    def rjust(self, width: int, fillchar: bytes) -> bytes: ...
+    def ljust(self, width: int, fillchar: bytes | bytearray = b" ") -> bytes: ...
+    def rjust(self, width: int, fillchar: bytes | bytearray = b" ") -> bytes: ...
 
 class bytearray:
     @overload