Fix pyproj dependency

[coveralls]

Pull Request Test Coverage Report for Build 270

• 19 of 27 (70.37%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+1.4%) to 81.426%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pysheds/grid.py	16	24	66.67%
<!--	Total:	19	27	70.37%	-->

Files with Coverage Reduction	New Missed Lines	%
pysheds/grid.py	1	83.78%
<!--	Total:	1		-->

Totals
Change from base Build 255:	1.4%
Covered Lines:	2021
Relevant Lines:	2482

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💛 - Coveralls