Update grpc-dart repo after The Move.
diff --git a/tools/interop_matrix/client_matrix.py b/tools/interop_matrix/client_matrix.py
index 943c235..83d75ec 100644
--- a/tools/interop_matrix/client_matrix.py
+++ b/tools/interop_matrix/client_matrix.py
@@ -18,7 +18,7 @@
 
 def get_github_repo(lang):
     return {
-        'dart': 'https://github.com/dart-lang/grpc-dart.git',
+        'dart': 'https://github.com/grpc/grpc-dart.git',
         'go': 'https://github.com/grpc/grpc-go.git',
         'java': 'https://github.com/grpc/grpc-java.git',
         'node': 'https://github.com/grpc/grpc-node.git',