[FLINK-24137][python] Fix the cases that Python boot process exits before Python SDK harness connects to the Java Operator in lookback mode

This closes #17219.
diff --git a/flink-python/setup.py b/flink-python/setup.py
index edc728e..34a0b31 100644
--- a/flink-python/setup.py
+++ b/flink-python/setup.py
@@ -292,7 +292,7 @@
         install_requires=['py4j==0.10.8.1', 'python-dateutil==2.8.0', 'apache-beam==2.19.0',
                           'cloudpickle==1.2.2', 'avro-python3>=1.8.1,<=1.9.1', 'jsonpickle==1.2',
                           'pandas>=0.23.4,<=0.25.3', 'pyarrow>=0.15.1,<0.16.0', 'pytz>=2018.3',
-                          'numpy>=1.14.3,<1.20'],
+                          'numpy>=1.14.3,<1.20', 'requests>=2.26.0'],
         cmdclass={'build_ext': build_ext},
         tests_require=['pytest==4.4.1'],
         description='Apache Flink Python API',