chore: update juju/juju requirement from ~> 0.12.0 to ~> 0.14.0

Updates the requirements on [juju/juju](https://github.com/juju/terraform-provider-juju) to permit the latest version.

Updates `juju/juju` to 0.14.0
- [Release notes](https://github.com/juju/terraform-provider-juju/releases)
- [Changelog](https://github.com/juju/terraform-provider-juju/blob/main/CHANGELOG.md)
- [Commits](juju/terraform-provider-juju@v0.12.0...v0.14.0)

---
updated-dependencies:
- dependency-name: juju/juju
  dependency-type: direct:production
  dependency-group: terraform_dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>

terraform/terraform.tf

@@ -5,7 +5,7 @@ terraform {
   required_providers {
     juju = {
       source  = "juju/juju"
-      version = "~> 0.12.0"
+      version = "~> 0.14.0"
     }
   }
 }