WP Mail SMTP Pro 4.2.0

### Added:
- Pro plugin translations for: Spanish (Spain), German, Portuguese (Brazil), Italian, French, Japanese, Polish, Dutch, Russian, Turkish.
- Email Log: ability to manually re-check email delivery status.
- Alerts: ability to test alerts.

### Changed:
- Moved the Email Test tab from the settings page to the tools page.
- Improved the dashboard widget settings' user experience.
- Removed Sendinblue SDK library because it was deprecated.
- Updated AWS SDK library to 3.277.11.
- Mailgun API instructions and webhooks verification process.

### Fixed:
- Debug Event details popup scrolling.
- Email logs import from the WP Mail Logging plugin caused by long non-English subjects.
- Conflict with other plugins (Alt Manager) that made the WP Plugins install page unusable.

### Changed:
- Improved notifications formatting and styles.
- Sendinblue rebranded to Brevo.

### Fixed:
- Explicitly set "Content-Type" header for the HTML test email.

### Fixed:
- Print email log headers data security issue.