Improve code

Created by: hatamiarash7

• Update packages
• Allows the user to define the metrics to be scraped
• Use const instead of let for variables that are not reassigned.
• Use async/await syntax consistently to handle promises.
• Add error handling to catch and log any errors that occur.
• Use template literals for string concatenation.
• Move the creation of the promClient.register.contentType variable to a separate variable declaration for improved readability.