feat(ci): move docker build to its own step

Jenkinsfile

@@ -13,18 +13,23 @@ pipeline {
 		stash includes: 'target/release/telegram-leetbot', name: 'app'
             }
         }
-    }
-
-    post {
-	success {
+	stage('docker build') {
+	    steps {
 		unstash 'app'
 
-	    archiveArtifacts artifacts: 'target/debug/telegram-leetbot', fingerprint: true
-
 		echo 'Starting docker image build'
 		script {
 		    docker.build("northcode/telegram-leetbot")
 		}
 	    }
 	}
+    }
+
+    post {
+	success {
+	    unstash 'app'
+	    
+	    archiveArtifacts artifacts: 'target/debug/telegram-leetbot', fingerprint: true
+	}
+    }
 }