remove unused variables (#4437)

##### Summary
<!--- Describe the change below, including rationale and design decisions -->
Removing variables which are not used in Python code
<!--- HINT: Include "Fixes #nnn" if you are fixing an existing issue -->

##### Component Name
<!--- Write the short name of the module or plugin below -->
- python.d.plugin
- portcheck python module
- postgres python module

##### Additional Information
<!--- Include additional information to help people understand the change here -->
<!--- A step-by-step reproduction of the problem is helpful if there is no related issue -->

<!--- Paste log output below, e.g. before and after your change -->
```paste below

```

1 files changed, 2 insertions, 2 deletions

diff --git a/collectors/python.d.plugin/python_modules/bases/FrameworkServices/SocketService.py b/collectors/python.d.plugin/python_modules/bases/FrameworkServices/SocketService.py
index 137693c38e..e854553078 100644
--- a/collectors/python.d.plugin/python_modules/bases/FrameworkServices/SocketService.py
+++ b/collectors/python.d.plugin/python_modules/bases/FrameworkServices/SocketService.py
@@ -38,7 +38,7 @@ class SocketService(SimpleService):
                                                                   message=message))
         else:
             if self.__socket_config is not None:
-                af, sock_type, proto, canon_name, sa = self.__socket_config
+                _, _, _, _, sa = self.__socket_config
                 self.error('socket to "{address}" port {port}: {message}'.format(address=sa[0],
                                                                                  port=sa[1],
                                                                                  message=message))
@@ -56,7 +56,7 @@ class SocketService(SimpleService):
                 self.error("Cannot create socket to 'None':")
                 return False
 
-        af, sock_type, proto, canon_name, sa = res
+        af, sock_type, proto, _, sa = res
         try:
             self.debug('Creating socket to "{address}", port {port}'.format(address=sa[0], port=sa[1]))
             self._sock = socket.socket(af, sock_type, proto)