CHORE: Fix lint warnings from golangci-lint #125

Job	Run time
integration-test-providers	8s
integration-tests (AXFRDDNS)	1m 46s
integration-tests (AXFRDDNS_DNSSEC)	2m 30s
integration-tests (AZURE_DNS)	9m 24s
integration-tests (BIND)	1m 32s
integration-tests (CLOUDFLAREAPI)	9m 10s
integration-tests (CNR)	9m 32s
integration-tests (DIGITALOCEAN)	4m 47s
integration-tests (GANDI_V5)	6m 48s
integration-tests (GCLOUD)	6m 0s
integration-tests (HEDNS)	15m 55s
integration-tests (HEXONET)	3m 43s
integration-tests (MYTHICBEASTS)	13m 19s
integration-tests (NS1)	5m 21s
integration-tests (ROUTE53)	4m 17s
integration-tests (SAKURACLOUD)	4m 10s
integration-tests (NAMEDOTCOM)	4m 56s
integration-tests (TRANSIP)	14m 21s
	1h 57m 39s

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