Import pre-existing Gitea branch protections

Why:
- tofu apply fails with "Branch protection already exist" because the nine
  repos protected in #60 already have live branch protection in Gitea that is
  absent from Terraform state, so Terraform tries to create rules that already
  exist and Gitea rejects them.
- The pinned go-gitea/gitea provider 0.7.0 defines no importer for
  gitea_repository_branch_protection, so the existing rules cannot be adopted
  on that version.

How:
- Bump the gitea provider from 0.7.0 to 0.8.1, which adds an importer for
  gitea_repository_branch_protection (id format <org>/<repo>/<rule_name>).
- Add import blocks adopting the nine existing branch protections into state
  instead of recreating them.

modules/gitea_instance/modules/branch_protection/terraform.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     gitea = {
       source  = "go-gitea/gitea"
-      version = "0.7.0"
+      version = "0.8.1"
     }
   }
 }

modules/gitea_instance/modules/deploy_key/terraform.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     gitea = {
       source  = "go-gitea/gitea"
-      version = "0.7.0"
+      version = "0.8.1"
     }
   }
 }

modules/gitea_instance/modules/organisation/terraform.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     gitea = {
       source  = "go-gitea/gitea"
-      version = "0.7.0"
+      version = "0.8.1"
     }
   }
 }

modules/gitea_instance/modules/repository/terraform.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     gitea = {
       source  = "go-gitea/gitea"
-      version = "0.7.0"
+      version = "0.8.1"
     }
   }
 }

modules/gitea_instance/modules/team/terraform.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     gitea = {
       source  = "go-gitea/gitea"
-      version = "0.7.0"
+      version = "0.8.1"
     }
   }
 }

modules/gitea_instance/modules/user/terraform.tf

@@ -3,7 +3,7 @@ terraform {
   required_providers {
     gitea = {
       source  = "go-gitea/gitea"
-      version = "0.7.0"
+      version = "0.8.1"
     }
     random = {
       source  = "hashicorp/random"