Pin pylint version to 2.17.7 in tox.ini

Change-Id: I765081c918c8e47b92a3c3c50247a0f98d482d2a
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/tox.ini b/tox.ini
index dc0145e..967513a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -172,7 +172,7 @@
 deps =  {[testenv]deps}
         -r{toxinidir}/requirements-dev.txt
         -r{toxinidir}/requirements-test.txt
-        pylint
+        pylint==2.17.7
 skip_install = true
 commands =
         pylint -E NG-RO/osm_ng_ro --disable=E1101