Nope. The Wild Hunt quotes scholar and Celtic Reconstructionist pagan P. Sufenas Virius Lupus:
“Unfortunately, this isn’t true, and the hagiographies of St. Patrick did not include this particular “miracle” until quite late, relatively speaking (his earliest hagiographies are from the 7th century, whereas this incident doesn’t turn up in any of them until the 11th century). St. Patrick’s reputation as the one who Christianized Ireland is seriously over-rated and overstated, as there were others that came before him (and after him), and the process seemed to be well on its way at least a century before the “traditional” date given as his arrival, 432 CE, because Irish colonists (yes, you read that right!) in southern Wales, Cornwall, and elsewhere in Roman and sub-Roman Britain had already come into contact with Christians and carried the religion back with them when visiting home.”
The Wild Hunt: Saint Patrick, Druids, Snakes, and Popular Myths
See also: Bring the Snakes Back to Ireland.