fix: update S3 backend config for Terraform init

Use non-deprecated s3 endpoint settings, switch to use_path_style, and trim newline characters from B2 credentials when generating backend.hcl in CI.

.gitea/workflows/terraform-plan.yml

@@ -26,14 +26,16 @@ jobs:
           bucket                      = "${{ secrets.B2_TF_BUCKET }}"
           key                         = "terraform.tfstate"
           region                      = "us-east-005"
-          endpoint                    = "${{ secrets.B2_TF_ENDPOINT }}"
-          access_key                  = "${{ secrets.B2_KEY_ID }}"
-          secret_key                  = "${{ secrets.B2_APPLICATION_KEY }}"
+          endpoints = {
+            s3 = "${{ secrets.B2_TF_ENDPOINT }}"
+          }
+          access_key                  = "$(printf '%s' "${{ secrets.B2_KEY_ID }}" | tr -d '\r\n')"
+          secret_key                  = "$(printf '%s' "${{ secrets.B2_APPLICATION_KEY }}" | tr -d '\r\n')"
           skip_credentials_validation = true
           skip_metadata_api_check     = true
           skip_region_validation      = true
           skip_requesting_account_id  = true
-          force_path_style            = true
+          use_path_style              = true
           EOF
           echo "Created secrets.auto.tfvars:"
           cat secrets.auto.tfvars | sed 's/=.*/=***/'