api: Add impl FromStr for MatrixVersion

Enables `str.parse::<MatrixVersion>()`.

crates/ruma-api/src/metadata.rs

@@ -1,6 +1,7 @@
 use std::{
     convert::TryFrom,
     fmt::{self, Display},
+    str::FromStr,
 };
 
 use http::Method;
@@ -111,6 +112,14 @@ impl TryFrom<&str> for MatrixVersion {
     }
 }
 
+impl FromStr for MatrixVersion {
+    type Err = UnknownVersionError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::try_from(s)
+    }
+}
+
 impl MatrixVersion {
     /// Checks whether a version is compatible with another.
     ///