Support to Sonar version 6.x, 7.x and 8.x

[odair-pedro]

Adjusts to support other sonar api versions

[coveralls]

Pull Request Test Coverage Report for Build 318512302

• 100 of 112 (89.29%) changed or added relevant lines in 11 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+7.8%) to 66.667%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
cmd/serverversion.go	9	10	90.0%
cmd/search.go	11	13	84.62%
cmd/validate.go	30	32	93.75%
cmd/root.go	12	15	80.0%
net/http/http.go	3	7	42.86%

Files with Coverage Reduction	New Missed Lines	%
cmd/root.go	1	83.33%
net/http/http.go	1	31.15%

Totals
Change from base Build 294528098:	7.8%
Covered Lines:	262
Relevant Lines:	393

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💛 - Coveralls