Allow deprecation to Error::description

We cannot simply remove it as it's a breaking change.

Signed-off-by: Yuki Okushi <jtitor@2k36.org>

Author: JohnTitor

src/lib.rs

@@ -293,6 +293,7 @@ impl GlobError {
 }
 
 impl Error for GlobError {
+    #[allow(deprecated)]
     fn description(&self) -> &str {
         self.error.description()
     }