Fix snapshot repository resource import

[ignuki]

trafficstars

Naive fix for #116

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[cla-checker-service[bot]]

❌ Author of the following commits did not sign a Contributor Agreement: 69b01ff794cfe322bde3c594e8ed013d2461a0ac, 76988986b8545c4080a1c3dad73d6669f73cb88a

Please, read and sign the above mentioned agreement if you want to contribute to this project

[tobio]

Fixed in https://github.com/elastic/terraform-provider-elasticstack/pull/187