fix: change import long to require (#394)

Source-Link: https://github.com/googleapis/synthtool/commit/d229a1258999f599a90a9b674a1c5541e00db588
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-nodejs:latest@sha256:74ab2b3c71ef27e6d8b69b1d0a0c9d31447777b79ac3cd4be82c265b45f37e5e