refactor(client): allow ?Sized trait objects in dns_resolver (#870)

Author: 0x676e67

src/client/http/mod.rs

@@ -1246,8 +1246,8 @@ impl ClientBuilder {
     /// Overrides for specific names passed to `resolve` and `resolve_to_addrs` will
     /// still be applied on top of this resolver.
     #[inline]
-    pub fn dns_resolver<R: Resolve + 'static>(mut self, resolver: Arc<R>) -> ClientBuilder {
-        self.config.dns_resolver = Some(resolver as _);
+    pub fn dns_resolver(mut self, resolver: Arc<dyn Resolve>) -> ClientBuilder {
+        self.config.dns_resolver = Some(resolver);
         self
     }