Fix clippy: Use is_empty() instead of comparing to empty string

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

Author: matthiasbeyer

src/env.rs

@@ -81,7 +81,7 @@ impl Source for Environment {
 
         for (key, value) in env::vars() {
             // Treat empty environment variables as unset
-            if self.ignore_empty && value == "" {
+            if self.ignore_empty && value.is_empty() {
                 continue;
             }