Merge pull request #10 from paganotoni/dependabot/go_modules/golang.org/x/crypto-0.45.0

Bump golang.org/x/crypto from 0.20.0 to 0.45.0

fixing other dependencies issues

solving security issues and updating Go version

Merge pull request #8 from dmuriel/task-custom-headers

Adding custom headers to sendgrid sender

prepending text/plain if present

adding cc and bcc, also adding all personalizations

content type needs to be set as base64

moving to modules and adding SetCustomArgs

Merge pull request #7 from tatang26/task-add-custom-args

Update custom args

Udpdate README.md and use fmt to cast interface in buildMail

Use Data Field to add custom args

Add custom args to SGMailV3