dev: Update references to default branch after renaming

Author: bd808

.github/workflows/tox.yml

@@ -2,7 +2,7 @@ name: tox
 on:
   push:
     branches:
-      - master
+      - main
   pull_request:
 
 concurrency:

docs/index.rst

@@ -13,7 +13,7 @@ IRC bot framework using mixins to provide commonly desired functionality.
    :target: https://python-ib3.readthedocs.io
 
 .. image:: https://img.shields.io/pypi/l/ib3.svg
-   :target: https://github.com/bd808/python-ib3/blob/master/COPYING
+   :target: https://github.com/bd808/python-ib3/blob/main/COPYING
 
 .. image:: https://img.shields.io/github/forks/bd808/python-ib3.svg?style=social&label=Fork
    :target: https://github.com/bd808/python-ib3