fix typo

Cargo.toml

diff --git a/Cargo.toml b/Cargo.toml
index 233d110..2b0e738 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,7 +7,7 @@
 license     = "Apache-2.0"
 name        = "redis-cache"
 repository  = "https://github.com/casbin-rs/redis-cache"
-version     = "0.2.0"
+version     = "0.3.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

src/lib.rs

diff --git a/src/lib.rs b/src/lib.rs
index ed3b7d2..a92e3b2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -85,7 +85,7 @@
     fn clear(&mut self) {
         let _ = redis::cmd("DEL")
             .arg(CACHE_HKEY)
-            .query::<String>(&mut self.conn);
+            .query::<bool>(&mut self.conn);
     }
 }