Log Message:
net/terraform-provider-vultr: Update to 2.11.1

The govultr and data type update fixes an issue where it was impossible to
remove the deprecated "tag" argument from an instance.

Upstream Release Notes:
 - Release v2.11.1 #patch
 - Bump govultr v1.17.0 and update data types
 - Fix vultr_instance_ipv4 resource doc and argument reference.
 - Fix incorrect import example