chore: Lower meta's minimum version

lib/src/omemo/sessionmanager.dart

@@ -415,13 +415,7 @@ class OmemoSessionManager {
   /// Returns the device map, i.e. the mapping of bare Jid to its device identifiers
   /// we have built sessions with.
   Future<Map<String, List<int>>> getDeviceMap() async {
-    Map<String, List<int>>? map;
-
-    await _lock.synchronized(() async {
-      map = _deviceMap;
-    });
-
-    return map!;
+    return _lock.synchronized(() => _deviceMap);
   }
 
   /// Removes the ratchet identified by [jid] and [deviceId] from the session manager.

pubspec.yaml

@@ -11,7 +11,7 @@ dependencies:
   collection: ^1.16.0
   cryptography: ^2.0.5
   hex: ^0.2.0
-  meta: ^1.8.0
+  meta: ^1.7.0
   pinenacl: ^0.5.1
   synchronized: ^3.0.0+2