[Snyk] Upgrade rxjs from 6.3.3 to 6.6.7

[snyk-kevin]

Snyk has created this PR to upgrade rxjs from 6.3.3 to 6.6.7.

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 14 versions ahead of your current version.

• The recommended version was released on 4 years ago.

Release notes

Package name: rxjs

• 6.6.7 - 2021-03-28
• 6.6.6 - 2021-02-25
• 6.6.4 - 2021-02-24
• 6.6.3 - 2020-09-06
• 6.6.2 - 2020-07-31
• 6.6.1 - 2020-07-31
• 6.6.0 - 2020-07-02
• 6.5.5 - 2020-04-03
• 6.5.4 - 2019-12-27
• 6.5.3 - 2019-09-03
• 6.5.2 - 2019-05-10
• 6.5.1 - 2019-04-23
• 6.5.0 - 2019-04-23
• 6.4.0 - 2019-01-30
• 6.3.3 - 2018-09-25

from rxjs GitHub release notes

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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.

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[snyk-kevin]

🎉 Snyk checks have passed. No issues have been found so far.

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