feat(CI): Sign .drone.yml

Signed-off-by: Joas Schilling <coding@schilljs.com>

.drone.jsonnet

@@ -152,4 +152,9 @@ local PipelinePostgreSQL(test_set) = Pipeline(
 	PipelinePostgreSQL("integration"),
 	PipelinePostgreSQL("sharing"),
 	PipelinePostgreSQL("sharing-2"),
+
+	{
+		kind: "signature",
+		hmac: "7d4f30bec296493e6f94fa268c8fb67ab927883875beda00b1d0f4c867bd825c"
+	},
 ]

.drone.yml

@@ -1354,3 +1354,6 @@ trigger:
   event:
   - pull_request
   - push
+---
+hmac: 7d4f30bec296493e6f94fa268c8fb67ab927883875beda00b1d0f4c867bd825c
+kind: signature