Fix coverage badge update problem #53

[Xhenet]

Replace the svg with a png

[coveralls]

Pull Request Test Coverage Report for Build 218

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 40.123%

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Totals
Change from base Build 212:	0.0%
Covered Lines:	522
Relevant Lines:	1301

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💛 - Coveralls