chore(deps): update dependency karma to v6.3.15

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
karma (source)	6.3.13 -> 6.3.15

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Release Notes

karma-runner/karma

### [`v6.3.15`](https://togithub.com/karma-runner/karma/blob/HEAD/CHANGELOG.md#​6315-httpsgithubcomkarma-runnerkarmacomparev6314v6315-2022-02-05) [Compare Source](https://togithub.com/karma-runner/karma/compare/v6.3.14...v6.3.15) ##### Bug Fixes - **helper:** make mkdirIfNotExists helper resilient to concurrent calls ([d9dade2](https://togithub.com/karma-runner/karma/commit/d9dade2f004a340e49c9a633177576200c286404)), closes [/github.com/karma-runner/karma-coverage/issues/434#issuecomment-1017939333](https://togithub.com//github.com/karma-runner/karma-coverage/issues/434/issues/issuecomment-1017939333) ### [`v6.3.14`](https://togithub.com/karma-runner/karma/blob/HEAD/CHANGELOG.md#​6314-httpsgithubcomkarma-runnerkarmacomparev6313v6314-2022-02-05) [Compare Source](https://togithub.com/karma-runner/karma/compare/v6.3.13...v6.3.14) ##### Bug Fixes - remove string template from client code ([91d5acd](https://togithub.com/karma-runner/karma/commit/91d5acda6325caf91685da465d688527bd412b47)) - warn when `singleRun` and `autoWatch` are `false` ([69cfc76](https://togithub.com/karma-runner/karma/commit/69cfc763c8f83e8e7e64d34e17829d0d3dcc0449)) - **security:** remove XSS vulnerability in `returnUrl` query param ([839578c](https://togithub.com/karma-runner/karma/commit/839578c45a8ac42fbc1d72105f97eab77dd3eb8a))

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Configuration

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🚦 Automerge: Enabled.

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