Update dependency karma to ~4.3.0

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
karma (source)	devDependencies	minor	~4.2.0 -> ~4.3.0

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Release Notes

karma-runner/karma

v4.3.0

Compare Source

Bug Fixes

• build: switch from yarn to package-lock.json (#​3351) (6c5add2)
• config: Simpilfy error proceesing. (#​3345) (582a406), closes #​3339
• deps: lodash update. (#​3341) (5614c04)
• server: Simplify 'dom' inclusion. (#​3356) (5f13e11)
• test: test:client silently failing on Travis (#​3343) (1489e9a), closes /travis-ci.org/karma-runner/karma/jobs/537027667#L1046
• travis: Pin to trusty (#​3347) (1c6c690)

Features

• async: frameworks can be loaded asynchronously (#​3297) (177e2ef), closes #​851
• config: socket.io server pingTimeout config option. (#​3355) (817fbbd)
• preprocessor: preprocessor_priority execution order. (#​3303) (c5f3560)
• runner: feat(runner): (62d4c5a), closes #​2121 #​2799 #​2121 #​2799

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