fix(run-task): bug deleting long path names with forward slashes on Windows

This is porting a fix that landed in mozfile (where this code was copied
from).

Bug: 1948871

Author: ahal

src/taskgraph/run-task/run-task

@@ -199,15 +199,15 @@ def remove(path):
         return
 
     """
-    On Windows, adds '\\\\?\\' to paths which match ^[A-Za-z]:\\.* to access
+    On Windows, adds '\\\\?\\' to paths which match ^[A-Za-z]:(\\|/).* to access
     files or directories that exceed MAX_PATH(260) limitation or that ends
     with a period.
     """
     if (
         sys.platform in ("win32", "cygwin")
         and len(path) >= 3
         and path[1] == ":"
-        and path[2] == "\\"
+        and path[2] in (os.pathsep, os.altsep)
     ):
         path = "\\\\?\\%s" % path