Use f-strings wherever possible (#3102)

codespell_lib/_codespell.py

diff --git a/codespell_lib/_codespell.py b/codespell_lib/_codespell.py
index ae6bc37..017a383 100644
--- a/codespell_lib/_codespell.py
+++ b/codespell_lib/_codespell.py
@@ -952,7 +952,7 @@
 
                 if options.write_changes and fix:
                     changed = True
-                    lines[i] = re.sub(r"\b%s\b" % word, fixword, lines[i])
+                    lines[i] = re.sub(rf"\b{word}\b", fixword, lines[i])
                     fixed_words.add(word)
                     continue