fix clippy warnings #173

Job	Run time
Clippy	1m 51s
Code Coverage	1m 44s
Build Wasm Examples (wasm-yew-minimal)	48s
Build Examples (3d_charts)	32s
Rustfmt	11s
Build Examples (basic_charts)	33s
Tests (ubuntu-latest)	2m 5s
Build Examples (custom_controls)	31s
Tests (windows-latest)	3m 57s
Tests (macos-latest)	1m 47s
Build Examples (financial_charts)	34s
Build Examples (images)	41s
Build Examples (kaleido)	1m 16s
Build Examples (maps)	32s
Build Examples (ndarray)	35s
Build Examples (scientific_charts)	35s
Build Examples (shapes)	35s
Build Examples (subplots)	33s
	19m 20s

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