Bump reno requirement to latest version and set default_branch (Qiski…

…t#1300)

When we switched to using main as the default branch for qiskit-aer
we encountered a bug in reno that required a branch named master to exist
for traversing the git history. To workaround that issue we temporarily
added back a branch named master while we waited for the fix [1] to be
included in a release. A new reno release has been published [2] and we
can rely on that version and delete the idle master branch now. This
commit makes this change and switches to using reno>=3.4.0 and uses
the new default_branch configuration option added in 3.4.0 to fix the
issue.

[1] https://opendev.org/openstack/reno/commit/ed6bbae82e01edf781534d9e9cce21e0c55a49a6
[2] https://pypi.org/project/reno/3.4.0/

releasenotes/notes/config.yaml

@@ -0,0 +1,3 @@
+---
+encoding: utf8
+default_branch: main

requirements-dev.txt

@@ -11,5 +11,5 @@ sphinx-rtd-theme>=0.4.0
 sphinx-tabs>=1.1.11
 sphinx-automodapi
 jupyter-sphinx;python_version<'3.8'
-reno>=3.1.0
+reno>=3.4.0
 ddt>=1.2.0,!=1.4.0