fix docker image build

Jenkinsfile

@@ -1,8 +1,5 @@
 pipeline {
     agent none
-    environment {
-        IMAGE_TAG = "git.dreamfall.space/thrrgilag/clacksme:latest"
-    }
     stages {
         stage('Build docker image') {
             agent { label 'docker-build' }
@@ -10,7 +7,7 @@ pipeline {
                 mattermostSend "Docker build started - ${env.JOB_NAME} ${env.BUILD_NUMBER} (<${env.BUILD_URL}|Open>)"
                 script {
                     docker.withRegistry('https://git.dreamfall.space/thrrgilag', 'docker-gitea-creds') {
-                        def customImage = docker.build(${env.IMAGE_TAG})
+                        def customImage = docker.build("git.dreamfall.space/thrrgilag/clacksme:latest")
                         customImage.push()
                     }
                 }