Upgrade pylint version to 3.1.1 and fix pylint issues in that version

Change-Id: Ibf16dc9af6b528a3d3fef38bd038519fa65966e2
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/n2vc/k8s_helm_base_conn.py b/n2vc/k8s_helm_base_conn.py
index fb5aa09..0748d59 100644
--- a/n2vc/k8s_helm_base_conn.py
+++ b/n2vc/k8s_helm_base_conn.py
@@ -1685,6 +1685,7 @@
         if env:
             environ.update(env)
 
+        process_1 = None
         try:
             async with self.cmd_lock:
                 read, write = os.pipe()