Change category output string to format string.

Change the category output string to a format string so that the
category is correctly logged out to the user when generating a category
graph.

Bug: T348709
Change-Id: I6d078ccabd5d69b143b4e4d0546aa7d96073d833
---
M scripts/category_graph.py
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/scripts/category_graph.py b/scripts/category_graph.py
index 0d875b2..58ae66d 100755
--- a/scripts/category_graph.py
+++ b/scripts/category_graph.py
@@ -71,7 +71,7 @@
             cat_title = pywikibot.input(
                 'For which category do you want to create a graph?')
 
-        pywikibot.info('Scanning {cat_title!r}')
+        pywikibot.info(f'Scanning {cat_title!r}')
         self.cat = pywikibot.Category(self.site, cat_title)
         self.to = args.to
         if self.to == '?':

