ruma-events: Add CancelCode variants for SAS verification

See: https://spec.matrix.org/v1.1/client-server-api/#verification-messages-specific-to-sas

crates/ruma-events/src/key/verification/cancel.rs

@@ -121,6 +121,14 @@ pub enum CancelCode {
     #[ruma_enum(rename = "m.accepted")]
     Accepted,
 
+    /// The device receiving this error can ignore the verification request.
+    #[ruma_enum(rename = "m.mismatched_commitment")]
+    MismatchedCommitment,
+
+    /// The SAS did not match.
+    #[ruma_enum(rename = "m.mismatched_sas")]
+    MismatchedSas,
+
     #[doc(hidden)]
     _Custom(String),
 }