[Snyk] Upgrade express from 4.17.1 to 4.21.2

[aarnold23]

Snyk has created this PR to upgrade express from 4.17.1 to 4.21.2.

ℹ️ Keep your dependencies up-to-date. This makes it easier to fix existing vulnerabilities and to more quickly identify and fix newly disclosed vulnerabilities when they affect your project.

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• The recommended version is 13 versions ahead of your current version.

• The recommended version was released 2 months ago.

Issues fixed by the recommended upgrade:

	Issue	Score	Exploit Maturity
	Regular Expression Denial of Service (ReDoS) SNYK-JS-PATHTOREGEXP-7925106	666	Proof of Concept
	Regular Expression Denial of Service (ReDoS) SNYK-JS-PATHTOREGEXP-8482416	666	Proof of Concept
	Cross-site Scripting (XSS) SNYK-JS-COOKIE-8163060	666	No Known Exploit
	Open Redirect SNYK-JS-EXPRESS-6474509	666	No Known Exploit
	Cross-site Scripting SNYK-JS-EXPRESS-7926867	666	No Known Exploit
	Cross-site Scripting SNYK-JS-SEND-7926862	666	No Known Exploit
	Cross-site Scripting SNYK-JS-SERVESTATIC-7926865	666	No Known Exploit

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Important

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

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