sh double quotations fix

Jenkinsfile

@@ -74,12 +74,12 @@ pipeline {
                         script {
                             installRetryCount = installRetryCount+1
                         }
-                        sh''' 
+                        sh"""
                         pip3 install --user -r requirements.txt
-                        wget $link
-                        python3 unzip.py $file
+                        wget ${link}
+                        python3 unzip.py ${file}
                         ls -la
-                        '''
+                        """
                     }
                 }
             }