Fix m.tz identifier and bias to stable.

Bump Ruma; enable spec versions 1.12 and 1.15.

Signed-off-by: Jason Volk <jason@zemos.net>

src/api/client/profile.rs

@@ -273,7 +273,7 @@ pub(crate) async fn get_profile_route(
 				("avatar_url", response.avatar_url.map(Into::into)),
 				("blurhash", response.blurhash),
 				("displayname", response.displayname),
-				("tz", response.tz),
+				("m.tz", response.tz),
 			];
 
 			let response = canonical_fields
@@ -314,7 +314,7 @@ pub(crate) async fn get_profile_route(
 		("avatar_url", avatar_url.map(Into::into)),
 		("blurhash", blurhash),
 		("displayname", displayname),
-		("tz", tz),
+		("m.tz", tz),
 	];
 
 	let response = canonical_fields

src/api/client/unversioned.rs

@@ -39,6 +39,8 @@ pub(crate) async fn get_supported_versions_route(
 			"v1.5".to_owned(),
 			"v1.10".to_owned(), // relations recursion
 			"v1.11".to_owned(), // authenticated media
+			"v1.12".to_owned(), // m.tz
+			"v1.15".to_owned(), // custom profile fields
 		],
 		unstable_features: BTreeMap::from_iter([
 			("org.matrix.e2e_cross_signing".to_owned(), true),