Merge pull request #43 from bnjjj/master

feat(CargoBuild): add env method to add environment variable to the cargo cmd

src/build.rs

@@ -1,4 +1,4 @@
-use std::ffi;
+use std::ffi::{self, OsStr};
 use std::process;
 
 use crate::cargo::Cargo;
@@ -177,6 +177,17 @@ impl CargoBuild {
         self.arg("--release")
     }
 
+    /// Inserts or updates an environment variable mapping.
+    pub fn env<K, V>(mut self, key: K, val: V) -> Self
+    where
+        K: AsRef<OsStr>,
+        V: AsRef<OsStr>,
+    {
+        self.cmd.env(key, val);
+
+        self
+    }
+
     /// Build artifacts in release mode if the current process has, with optimizations.
     #[cfg(debug_assertions)]
     pub fn current_release(self) -> Self {