Pin flake8 version while flake issues are being fixed

Change-Id: I1a5250946ff95eb74e7cf77935a51844573c74b6
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/tox.ini b/tox.ini
index 268ae78..f106d06 100644
--- a/tox.ini
+++ b/tox.ini
@@ -55,7 +55,7 @@
 
 #######################################################################################
 [testenv:flake8]
-deps = flake8
+deps = flake8==7.1.2
 commands =
         flake8 osm_lcm/ setup.py