Fix a warning from python setuptools. (ros2#1312)

In particular, the 'script-dir' and 'install-scripts'
keys are deprecated in favor of 'script_dir' and
'install_scripts', respectively.

Signed-off-by: Chris Lalancette <[email protected]>

Author: clalancette

rosbag2_examples/rosbag2_examples_py/setup.cfg

@@ -1,4 +1,4 @@
 [develop]
-script-dir=$base/lib/rosbag2_examples_py
+script_dir=$base/lib/rosbag2_examples_py
 [install]
-install-scripts=$base/lib/rosbag2_examples_py
+install_scripts=$base/lib/rosbag2_examples_py