[Snyk] Security upgrade bootstrap from 3.4.1 to 4.0.0

[stepek]

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

Snyk changed the following file(s):

• package.json

Vulnerabilities that will be fixed with an upgrade:

	Issue	Score
	Cross-site Scripting (XSS) SNYK-JS-BOOTSTRAP-10176066	498

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🦉 Cross-site Scripting (XSS)