[Snyk] Security upgrade express from 4.19.2 to 4.21.0

[pedily]

Snyk has created this PR to fix 1 vulnerabilities in the npm dependencies of this project.

Snyk changed the following file(s):

• package.json
• package-lock.json

Vulnerabilities that will be fixed with an upgrade:

	Issue	Score
	Cross-site Scripting SNYK-JS-SEND-7926862	391

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[!IMPORTANT]

• Check the changes in this PR to ensure they won't cause issues with your project.
• Max score is 1000. Note that the real score may have changed since the PR was raised.
• This PR was automatically created by Snyk using the credentials of a real user.

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🦉 Cross-site Scripting

[XavierJordaMurria]

:tada: This PR is included in version 1.5.1 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: