Repository: plotters-rs/plotters (language: rust)

Issue:
[BUG] "sans-serf" typo
**Describe the bug**
A trivial bug, a "sans-serf" typo in `axes3d.rs`

**To Reproduce**
```rust
use plotters::prelude::*;
let drawing_area = SVGBackend::new("configure_axes.svg", (300, 200)).into_drawing_area();
drawing_area.fill(&WHITE).unwrap();
let mut chart_builder = ChartBuilder::on(&drawing_area);
let mut chart_context = chart_builder.build_cartesian_3d(0.0..4.0, 0.0..4.0, 0.0..4.0).unwrap();
chart_context.configure_axes().x_labels(0).z_labels(0).draw().unwrap();
```

The resulting SVG file includes the `sans-serf` font in its source code. The browser substitutes a correct font, so this typo is actually innocuous.

**Version Information**
Plotters master [a72bfbc](https://github.com/plotters-rs/plotters/commit/a72bfbced3523b17adc974ec7459f6c1c6f2d986)



Discussion / hints:

Fix patch:
diff --git a/src/chart/axes3d.rs b/src/chart/axes3d.rs
index e19a056f..5f5830b7 100644
--- a/src/chart/axes3d.rs
+++ b/src/chart/axes3d.rs
@@ -141,7 +141,7 @@ where
             light_line_style: Into::<ShapeStyle>::into(&TRANSPARENT),
             axis_panel_style: Into::<ShapeStyle>::into(&BLACK.mix(0.1)),
             axis_style: Into::<ShapeStyle>::into(&BLACK.mix(0.8)),
-            label_style: ("sans-serf", (12).percent().max(12).in_pixels(&parent_size)).into(),
+            label_style: ("sans-serif", (12).percent().max(12).in_pixels(&parent_size)).into(),
             format_x: &X::format,
             format_y: &Y::format,
             format_z: &Z::format,


Test patch: