I don't think the annihilator method can be used or I don't know how to use it with a PDE.
What about the method of undetermined coeffeints? The right hand side is a degree zero polynomial, so the particular solution must be a degree zero polynomial(a constant)
What about the method of undetermined coeffeints? The right hand side is a degree zero polynomial, so the particular solution must be a degree zero polynomial(a constant)