Fix: naming condition (#72)

* fix: correct resource name condition

The condition for Log Analytics Workspace name is currently incorrect. The correct condition as per Microsoft documentation is: "4-63 chars, Alphanumerics and hyphens. Start and end with alphanumeric."

source: https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/resource-name-rules#microsoftoperationalinsights

* correct resource naming regex

According to Azure portal, the correct condition is:
- The workspace name must be between 4 and 63 characters.
- The workspace name can contain only letters, numbers and '-'. The '-' shouldn't be the first or the last symbol.

variables.tf

@@ -10,7 +10,7 @@ variable "name" {
   nullable    = false
 
   validation {
-    condition     = can(regex("^[A-Za-z0-9-]{4,63}$", var.name))
+    condition     = can(regex("^[A-Za-z0-9][A-Za-z0-9-]{2,61}[A-Za-z0-9]$", var.name))
     error_message = "The name must be a valid Log Analytics Workspace name."
   }
 }