client-api: Fix type of rank in search::search_events::v3::SearchResult

It is defined in the spec as a number, not an integer.

crates/ruma-client-api/CHANGELOG.md

@@ -1,5 +1,10 @@
 # [unreleased]
 
+Breaking changes:
+
+- Define `rank` as an `Option<f64>` instead of an `Option<UInt>` in
+  `search::search_events::v3::SearchResult`
+
 Improvements:
 
 - Add convenience constructors for enabling lazy-loading in filters 

crates/ruma-client-api/src/search/search_events.rs

@@ -435,7 +435,7 @@ pub mod v3 {
         ///
         /// Higher is closer.
         #[serde(skip_serializing_if = "Option::is_none")]
-        pub rank: Option<UInt>,
+        pub rank: Option<f64>,
 
         /// The event that matched.
         #[serde(skip_serializing_if = "Option::is_none")]