ci: activate ldap on arm64

.drone.yml

@@ -304,6 +304,9 @@ services:
     image: postgres:9.5
     environment:
       POSTGRES_DB: test
+  - name: ldap
+    pull: default
+    image: gitea/test-openldap:latest
 
 steps:
   - name: fetch-tags
@@ -338,7 +341,7 @@ steps:
     environment:
       GOPROXY: off
       TAGS: bindata
-      TEST_LDAP: 0
+      TEST_LDAP: 1
     depends_on:
       - build