west: runners: Fix typo'd log.wrn() call

Should be wrn() instead of warn(). Reported by pylint.

Also remove a {} from the message. It's not being formatted.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

scripts/west_commands/run_common.py

@@ -371,7 +371,7 @@ def _dump_context(command, args, runner_args, cached_runner_var):
             colorize=True)
 
     if cache is None:
-        log.warn('Missing or invalid CMake cache {}; there is no context.',
+        log.wrn('Missing or invalid CMake cache; there is no context.',
                 'Use --build-dir to specify the build directory.')
         return