dynamic conda finding

tracking_re_id/launch/single_person_demo.launch.py

@@ -1,14 +1,17 @@
 """Launch single_person_loc_node using the mmpose conda environment's Python."""
 
 import os
+import sys
+
+sys.path.insert(0, os.path.dirname(__file__))
+from _conda_utils import find_conda_python  # noqa: E402
+
 from launch import LaunchDescription
 from launch.actions import ExecuteProcess
 
 
 def generate_launch_description():
-    python_exe = os.path.expanduser(
-        '~/miniconda3/envs/mmpose/bin/python3'
-    )
+    python_exe = find_conda_python('mmpose')
 
     node_module = 'tracking_re_id.single_person_loc_node'