cli: remove format() left over in f63e56f

- The format() call was missing in the first place for `filename`.
- Other format() calls are obviously useless now that f-strings
  perform string interpolation.

yamllint/cli.py

@@ -79,9 +79,9 @@ def standard_color(problem, filename):
 
     @staticmethod
     def github(problem, filename):
-        line = f'::{problem.level} file={format(filename)},' \
-               f'line={format(problem.line)},col={format(problem.column)}' \
-               f'::{format(problem.line)}:{format(problem.column)} '
+        line = f'::{problem.level} file={filename},' \
+               f'line={problem.line},col={problem.column}' \
+               f'::{problem.line}:{problem.column} '
         if problem.rule:
             line += f'[{problem.rule}] '
         line += problem.desc