When using winrm config block, we had an address issue. This is no
longer a set but a list (As a list fits it more approp)
```
make testacc TEST=./builtin/providers/azurerm
TESTARGS='-run=TestAccAzureRMVirtualMachine_'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /vendor/)
TF_ACC=1 go test ./builtin/providers/azurerm -v
-run=TestAccAzureRMVirtualMachine_ -timeout 120m
=== RUN TestAccAzureRMVirtualMachine_basicLinuxMachine
--- PASS: TestAccAzureRMVirtualMachine_basicLinuxMachine (587.80s)
=== RUN TestAccAzureRMVirtualMachine_tags
--- PASS: TestAccAzureRMVirtualMachine_tags (554.53s)
=== RUN TestAccAzureRMVirtualMachine_updateMachineSize
--- PASS: TestAccAzureRMVirtualMachine_updateMachineSize (612.52s)
=== RUN TestAccAzureRMVirtualMachine_basicWindowsMachine
--- PASS: TestAccAzureRMVirtualMachine_basicWindowsMachine (765.90s)
=== RUN TestAccAzureRMVirtualMachine_windowsUnattendedConfig
--- PASS: TestAccAzureRMVirtualMachine_windowsUnattendedConfig
(770.53s)
=== RUN TestAccAzureRMVirtualMachine_winRMConfig
--- PASS: TestAccAzureRMVirtualMachine_winRMConfig (827.90s)
PASS
ok github.com/hashicorp/terraform/builtin/providers/azurerm
4119.192s
```
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