Updating docker pipeline to trigger off of tags

.drone.yml

@@ -3,11 +3,8 @@ type: docker
 name: chessboard_builder
 
 trigger:
-  branch:
-    - build_tools
   event:
-    - push
+    - tag
-    - custom
 
 steps:
   - name: docker
@@ -19,6 +16,13 @@ steps:
         from_secret: docker_username
       password:
         from_secret: docker_password
+      tags:
+        - latest
+        - ${DRONE_TAG//"builder-v"}
+    when:
+      ref:
+        include:
+          - ref/tags/builder-v*
 
 
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