Description: make regex a raw string, to avoid DeprecationWarning for invalid escapes
Author: Gordon Ball <gordon@chronitis.net>

--- a/humanize/number.py
+++ b/humanize/number.py
@@ -45,7 +45,7 @@
     except (TypeError, ValueError):
         return value
     orig = str(value)
-    new = re.sub("^(-?\d+)(\d{3})", '\g<1>,\g<2>', orig)
+    new = re.sub(r"^(-?\d+)(\d{3})", '\g<1>,\g<2>', orig)
     if orig == new:
         return new
     else: