use python library 're' instead of 'regex' for portability

src/Mod/Path/PathScripts/post/grbl_post.py

@@ -31,7 +31,7 @@ import argparse
 import datetime
 import shlex
 import PathScripts.PathUtil as PathUtil
-import regex
+import re
 
 
 TOOLTIP = """
@@ -580,7 +580,7 @@ def parse(pathobj):
                 out += linenumber() + format_outstring(outstring) + "\n"
 
             # Check for comments containing machine-specific commands to pass literally to the controller
-            m = regex.match(r'^\(MC_RUN_COMMAND: ([^)]+)\)$', command)
+            m = re.match(r'^\(MC_RUN_COMMAND: ([^)]+)\)$', command)
             if m:
                 raw_command = m.group(1)
                 out += linenumber() + raw_command + "\n"