Fix “docker rmi“ failure

Author: takezoe

src/main/scala/io/github/gitbucket/ci/manager/BuildJobThread.scala

@@ -267,7 +267,7 @@ class BuildJobThread(queue: LinkedBlockingQueue[BuildJob], threads: LinkedBlocki
       sb.append(s"${runContainerCommand}\n")
       val exitCode = runProcess(job, buildDir, workspaceDir, runContainerCommand)
 
-      val imageId = Process(s"""${dockerCommand} images --format "{{.ID}}" ${tagName}""").!!.stripLineEnd
+      val imageId = Process(s"""${dockerCommand} images --format {{.ID}} ${tagName}""").!!.stripLineEnd
       val rmImageCommand = s"${dockerCommand} rmi --force ${imageId}"
       sb.append(s"$rmImageCommand\n")
       runProcess(job, buildDir, workspaceDir, rmImageCommand)