Answer:
Hyperbole
Step-by-step explanation:
Hyperbole is a figure of speech that employs exaggeration as a rhetorical device. Hyperbole is mostly used in order to evoke strong feelings or create lasting impressions. More importantly, hyperbole is not meant to be taken seriously. In this case, Swift is using hyperbole when he emphasizes the fact that he has no personal interest in promoting the work.