fix parameter running out of bounds causes by wrong index

[coveralls]

Pull Request Test Coverage Report for Build 873

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 89.779%

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Files with Coverage Reduction	New Missed Lines	%
spotpy/algorithms/dream.py	1	88.73%
<!--	Total:	1		-->

Totals
Change from base Build 871:	0.02%
Covered Lines:	4137
Relevant Lines:	4608

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💛 - Coveralls