fix drone definition

.drone.star

@@ -137,9 +137,6 @@ def main(ctx):
     releaseSubmodule(ctx),
   ]
 
-  purge = purgeBuildArtifactCache(ctx, 'ocis-binary-amd64')
-  purge['depends_on'] = getPipelineNames(testPipelines(ctx) + [benchmark(ctx)])
-
   after = [
     manifest(ctx),
     changelog(ctx),
@@ -147,11 +144,16 @@ def main(ctx):
     badges(ctx),
     docs(ctx),
     updateDeployment(ctx),
-    purge,
   ]
 
   if ctx.build.event == "cron":
     before.append(benchmark(ctx))
+    
+    purge = purgeBuildArtifactCache(ctx, 'ocis-binary-amd64')
+    purge['depends_on'] = getPipelineNames(before)
+
+    before.append(purge)
+
     notify_pipeline = notify(ctx)
     notify_pipeline['depends_on'] = \
       getPipelineNames(before)
@@ -174,11 +176,17 @@ def main(ctx):
 
     pipelines = docs_pipelines + [ notify_pipeline ]
 
-  elif '[with-benchmarks]' in (ctx.build.title + ctx.build.message):
-    before.append(benchmark(ctx))
-
   else:
-    pipelines = before + stages + after
+    purge_dependencies = testPipelines(ctx)
+
+    if '[with-benchmarks]' in (ctx.build.title + ctx.build.message):
+      before.append(benchmark(ctx))
+      purge_dependencies.append(benchmark(ctx))      
+
+    purge = purgeBuildArtifactCache(ctx, 'ocis-binary-amd64')
+    purge['depends_on'] = getPipelineNames(purge_dependencies)
+    
+    pipelines = before + stages + after + [purge]
 
     notify_pipeline = notify(ctx)
     notify_pipeline['depends_on'] = \