[FLINK-24287][python][tests] Update grpcio version in tox.ini (#17301)

diff --git a/flink-python/tox.ini b/flink-python/tox.ini
index 475a316..ccd2c0a 100644
--- a/flink-python/tox.ini
+++ b/flink-python/tox.ini
@@ -30,7 +30,7 @@
     pytest
     apache-beam==2.27.0
     cython==0.29.16
-    grpcio>=1.17.0,<=1.26.0
+    grpcio>=1.29.0,<2
     grpcio-tools>=1.3.5,<=1.14.2
     apache-flink-libraries
 passenv = *