Update gdb & Victor's guide links, and fix voters link ignore (#1051)

* [PATCH]#1044 fixing victor stinner's guide link

* fixed conf.py and advanced-tools/gdb.rst link issues

* changes made in gbd.rst

Author: Dev-satish

advanced-tools/gdb.rst

@@ -21,7 +21,7 @@ GDB 7 and later
 ===============
 
 In gdb 7, support for `extending gdb with Python
-<https://sourceware.org/gdb/current/onlinedocs/gdb/Python.html#Python>`_ was
+<https://sourceware.org/gdb/onlinedocs/gdb/Python.html>`_ was
 added. When CPython is built you will notice a ``python-gdb.py`` file in the
 root directory of your checkout. Read the module docstring for details on how
 to use the file to enhance gdb for easier debugging of a CPython process.

conf.py

@@ -81,7 +81,7 @@
 
 linkcheck_ignore = [
     # The voters repo is private and appears as a 404
-    'https://github.com/python/voters/',
+    'https://github.com/python/voters',
     # The python-core team link is private, redirects to login
     'https://github.com/orgs/python/teams/python-core',
     # The Discourse groups are private unless you are logged in