improve: don't run sonar on dependabot PRs #6649

Job	Run time
sample_operators_tests (sample-operators/mysql-schema)	2m 38s
sample_operators_tests (sample-operators/leader-election)	3m 21s
sample_operators_tests (sample-operators/tomcat-operator)	2m 55s
sample_operators_tests (sample-operators/webpage)	3m 16s
sample_operators_tests (sample-operators/metrics-processing)	17m 48s
	29m 58s

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