Add exercise `speed_transformation` subject and test

rust/tests/speed_transformation_test/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "speed_transformation"
+version = "0.1.0"
+
+[[package]]
+name = "speed_transformation_test"
+version = "0.1.0"
+dependencies = [
+ "speed_transformation",
+]

rust/tests/speed_transformation_test/Cargo.toml

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+[package]
+name = "speed_transformation_test"
+version = "0.1.0"
+authors = ["Augusto <aug.ornelas@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+speed_transformation = { path = "../../../../rust-piscine-solutions/speed_transformation"}

rust/tests/speed_transformation_test/src/main.rs

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+// Create a function that receives the speed in km/h (kilometers per hour) and returns the
+// equivalent in m/s (meters per second)
+
+use speed_transformation::*;
+
+fn main() {
+	let km_h = 100.0;
+	let m_s = km_per_hour_to_meters_per_second(km_h);
+	println!("{} km/h is equivalent to {} m/s", km_h, m_s);
+}
+
+#[test]
+fn kmh_to_ms() {
+	assert_eq!(km_per_hour_to_meters_per_second(90.0), 25.0);
+	assert_eq!(km_per_hour_to_meters_per_second(50.0), 13.88888888888889);
+	assert_eq!(km_per_hour_to_meters_per_second(10.0), 2.7777777777777777);
+	assert_eq!(km_per_hour_to_meters_per_second(100.0), 27.77777777777778);
+}

subjects/speed_transformation/README.md

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+## speed_transformation
+
+### Instructions
+
+Create a function that receives the speed in km/h (kilometers per hour) and returns the equivalent in m/s (meters per second)
+
+### Expected Function
+
+```rust
+pub fn km_per_hour_to_meters_per_second(km_h: f64) -> f64 {
+	(10.0 / 36.0) * km_h
+}
+```
+
+### Usage
+
+```rust
+fn main() {
+	let km_h = 100.0;
+	let m_s = km_per_hour_to_meters_per_second(km_h);
+	println!("{} km/h is equivalent to {} m/s", km_h, m_s);
+}
+```
+
+And its output:
+
+```console
+student@ubuntu:~/[[ROOT]]/test$ cargo run
+100 km/h is equivalent to 27.77777777777778 m/s
+student@ubuntu:~/[[ROOT]]/test$
+```