Remove quotes from EngFormatter.format_eng example

ksunden · ksunden · commit 056fd64a3ed5 · 2022-12-13T16:37:39.000-06:00
This function does not, in fact, work when provided string input as
implied by the current docstring.
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -1432,7 +1432,7 @@ def format_eng(self, num):
         >>> format_eng(1000000)  # for self.places = 1
         '1.0 M'
 
-        >>> format_eng("-1e-6")  # for self.places = 2
+        >>> format_eng(-1e-6)  # for self.places = 2
         '-1.00 \N{MICRO SIGN}'
         """
         sign = 1
