Add mul_low and pow_trunc to protocol epoly_p

Author: remyoudompheng

src/flint/typing.py

@@ -143,6 +143,8 @@ def gcd(self, other: Self | _Tscalar, /) -> Self: ...
     def factor(self) -> tuple[_Tscalar, list[tuple[Self, int]]]: ...
     def factor_squarefree(self) -> tuple[_Tscalar, list[tuple[Self, int]]]: ...
     def deflation(self) -> tuple[Self, int]: ...
+    def mul_low(self, other: Self, n: int) -> Self: ...
+    def pow_trunc(self, e: int, n: int) -> Self: ...
 
 
 class _series_p(elem_p, Protocol[_Tscalar]):