Fix example to also normalize plus character in emails

[lucasra1]

Correct function to follow documentation. + characters also need to be removed and normalization is not only for gmail.com or googlemail.com addresses

https://developers.google.com/google-ads/api/docs/conversions/upload-offline#prepare-data

For email addresses:

• Remove all periods (.) in the username (before the @ symbol). For example,
  jane.doe@example.com becomes janedoe@example.com.
• Remove the plus (+) symbol and any characters following it in the username (before the @
  symbol). For example, janedoe+newsletter@example.com becomes janedoe@example.com.

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[BenRKarl]

Thank you for submitting this PR! I'm conferring internally on some of the details here to make sure I understand the functionality. In the meantime can you look at the CLA mentioned here?

[lucasra1]

Thank you for submitting this PR! I'm conferring internally on some of the details here to make sure I understand the functionality. In the meantime can you look at the CLA mentioned here?

If I am not mistaken I have agreed to it and rerun the GitHub Action successfully