Pin flake8 version while flake issues are being fixed

Change-Id: I1a5250946ff95eb74e7cf77935a51844573c74b6
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>

tox.ini

@@ -55,7 +55,7 @@ allowlist_externals = sh
 
 #######################################################################################
 [testenv:flake8]
-deps = flake8
+deps = flake8==7.1.2
 commands =
         flake8 osm_lcm/ setup.py