Fix passing envvars to closure in build

vars/buildStage.groovy

@@ -15,9 +15,7 @@ void call(Map config = [:], Closure body = { }) {
         }
         withEnv(["TAG=${runConfig.tag}", "HASH=${runConfig.hash}", "VERSION=${runConfig.version}"]) {
             if ( fileExists(runConfig.buildRequires)) {
-                sh """
-                    ${runConfig.buildCmd}
-                """
+                sh runConfig.buildCmd
             } else {
                 error("ERROR: File ${runConfig.buildRequires} does not exist in workspace.")
             }