Say we're running pylint

Now that the script might additionally run mypy, it's more
user-friendly to indicate what's going on at the beginning as well.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/scripts/check-python-files.sh

diff --git a/tests/scripts/check-python-files.sh b/tests/scripts/check-python-files.sh
index 11e351b..df4821a 100755
--- a/tests/scripts/check-python-files.sh
+++ b/tests/scripts/check-python-files.sh
@@ -62,6 +62,7 @@
     exit
 fi
 
+echo 'Running pylint ...'
 $PYTHON -m pylint -j 2 scripts/mbedtls_dev/*.py scripts/*.py tests/scripts/*.py || {
     echo >&2 "pylint reported errors"
     ret=1