remove useless mut declaration

[Paolo-Azzini]

No description provided.

[github-actions]

Coverage Report

Coverage after merging fix-pcg into master will be

85.65%

Coverage Report for Changed Files

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
camera.rs	89.69%	100%	72.22%	93.67%
cli.rs	0%	100%	0%	0%	100–401, 407, 55–99
error.rs	0%	100%	0%	0%	10, 31, 39, 46, 57, 90
main.rs	0.71%	100%	3.57%	0.40%	100–182, 184–188, 191–201, 203, 205–223, 228–280, 282, 284–302, 53–58, 60, 67–88, 93–99
material.rs	99.25%	100%	100%	99.12%	110, 299
render.rs	98.95%	100%	100%	98.86%	154, 170
scene.rs	97.49%	100%	93.15%	97.71%	1090, 114, 1169, 1184, 1226–1231, 193–195, 290–292, 432, 482, 498, 515, 525, 535, 554, 557, 600, 722, 743, 832, 897–898, 979
shape.rs	99.33%	100%	96.43%	99.53%	172, 24
world.rs	96.36%	100%	100%	95.92%	37, 43

[github-actions]

Coverage Report

Coverage after merging fix-pcg into master will be

85.83%

Coverage Report for Changed Files

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
render.rs	98.56%	100%	100%	98.43%	121, 137

[andros21]

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