Fix CI pipeline

Author: jc21

Jenkinsfile

@@ -5,9 +5,9 @@ pipeline {
   }
   agent any
   environment {
-      IMAGE_NAME      = nginx-proxy-manager
-      TEMP_IMAGE_NAME = nginx-proxy-manager-build_${BUILD_NUMBER}
-    }
+    IMAGE_NAME      = "nginx-proxy-manager"
+    TEMP_IMAGE_NAME = "nginx-proxy-manager-build_${BUILD_NUMBER}"
+  }
   stages {
     stage('Prepare') {
         steps {
@@ -37,9 +37,9 @@ node-prune'''
       }
     }
     stage('Build') {
-      steps {
-        def TAG_VERSION = getPackageVersion()
+      def TAG_VERSION = getPackageVersion()
 
+      steps {
         sh '''docker build -t $TEMP_IMAGE_NAME .
 exit $?'''
       }