chore: fix main branch (#102)

Author: ssbarnea

.github/workflows/tox.yml

@@ -5,7 +5,7 @@ on:
     tags:  # any tag regardless of its name, no branches
   push:  # only publishes pushes to the main branch to TestPyPI
     branches:  # any integration branch but not tag
-      - "master"
+      - "main"
     tags-ignore:
       - "**"
   pull_request: