CI: skip build steps for cron update works (#14443)

Signed-off-by: a101211279 <1012112796@qq.com>

.drone.yml

@@ -10,6 +10,12 @@ workspace:
   base: /go
   path: src/code.gitea.io/gitea
 
+trigger:
+  event:
+    - push
+    - tag
+    - pull_request
+
 steps:
   - name: deps-frontend
     pull: always
@@ -131,6 +137,12 @@ platform:
 depends_on:
   - compliance
 
+trigger:
+  event:
+    - push
+    - tag
+    - pull_request
+
 workspace:
   base: /go
   path: src/code.gitea.io/gitea
@@ -306,6 +318,12 @@ platform:
 depends_on:
   - compliance
 
+trigger:
+  event:
+    - push
+    - tag
+    - pull_request
+
 workspace:
   base: /go
   path: src/code.gitea.io/gitea
@@ -662,6 +680,12 @@ platform:
 depends_on:
   - compliance
 
+trigger:
+  event:
+    - push
+    - tag
+    - pull_request
+
 steps:
   - name: build-docs
     pull: always