bump plotly version and edition to 2021 #377

Job	Run time
Rustfmt	14s
semver	1m 10s
Clippy	2m 53s
Build Examples (3d_charts)	25s
Code Coverage	1m 51s
Build Wasm Examples (wasm-yew-minimal)	52s
Build Examples (basic_charts)	28s
Tests (ubuntu-latest)	1m 52s
Build Examples (custom_controls)	23s
Tests (windows-latest)	4m 50s
Build Examples (financial_charts)	21s
Tests (macos-latest)	1m 58s
Build Examples (images)	42s
Build Examples (kaleido)	1m 39s
Build Examples (maps)	21s
Build Examples (ndarray)	31s
Build Examples (scientific_charts)	22s
Build Examples (shapes)	26s
Build Examples (subplots)	23s
	21m 41s

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