switch default branch to main from master

refs manubot/rootstock#349

.github/workflows/release.yml

@@ -22,7 +22,7 @@ jobs:
       run: python -m build --sdist --wheel --outdir=dist
     - name: Deploy package
       if: '!github.event.repository.fork'
-      uses: pypa/gh-action-pypi-publish@master
+      uses: pypa/gh-action-pypi-publish@v1.4.1
       with:
         user: __token__
         password: ${{ secrets.pypi_password }}

.github/workflows/test.yml

@@ -91,7 +91,7 @@ jobs:
         export PYTHONPATH=.
         portray as_html --overwrite --output_dir=docs
     - name: Deploy docs
-      if: github.ref == 'refs/heads/master' && github.event_name == 'push' && !github.event.repository.fork
+      if: github.ref == 'refs/heads/main' && github.event_name == 'push' && !github.event.repository.fork
       uses: peaceiris/actions-gh-pages@v3
       with:
         github_token: ${{ secrets.GITHUB_TOKEN }}

README.md

@@ -5,8 +5,8 @@
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg?style=for-the-badge&logo=Python&logoColor=white)](https://github.com/psf/black)
 
 [![GitHub Actions CI Tests Status](https://img.shields.io/github/workflow/status/manubot/manubot/Tests?label=actions&logo=github&style=for-the-badge)](https://github.com/manubot/manubot/actions)
-[![Travis Linux Build Status](https://img.shields.io/travis/com/manubot/manubot/master?style=for-the-badge&logo=travis&label=Travis)](https://travis-ci.com/manubot/manubot)
-[![AppVeyor Windows Build Status](https://img.shields.io/appveyor/build/manubot/manubot/master?style=for-the-badge&logo=appveyor&logoColor=white&label=AppVeyor)](https://ci.appveyor.com/project/manubot/manubot/branch/master)
+[![Travis Linux Build Status](https://img.shields.io/travis/com/manubot/manubot/main?style=for-the-badge&logo=travis&label=Travis)](https://travis-ci.com/manubot/manubot)
+[![AppVeyor Windows Build Status](https://img.shields.io/appveyor/build/manubot/manubot/main?style=for-the-badge&logo=appveyor&logoColor=white&label=AppVeyor)](https://ci.appveyor.com/project/manubot/manubot/branch/main)
 
 
 [Manubot](https://manubot.org/ "Manubot homepage") is a workflow and set of tools for the next generation of scholarly publishing.
@@ -362,7 +362,7 @@ TAG=v$(python setup.py --version)
 
 # fetch tags from the upstream remote
 # (assumes upstream is the manubot organization remote)
-git fetch --tags upstream master
+git fetch --tags upstream main
 # get previous release tag, can hardcode like OLD_TAG=v0.3.1
 OLD_TAG=$(git describe --tags --abbrev=0)
 ```
@@ -385,7 +385,7 @@ echo $'\n\nCode authors\n------------\n' >> "release-notes/$TAG.md"
 git log $OLD_TAG..HEAD --format='%aN <%aE>' | sort --unique >> "release-notes/$TAG.md"
 ```
 
-After a commit with the above updates is part of `upstream:master`,
+After a commit with the above updates is part of `upstream:main`,
 for example after a PR is merged,
 use the [GitHub interface](https://github.com/manubot/manubot/releases/new) to create a release with the new "Tag version".
 Monitor [GitHub Actions](https://github.com/manubot/manubot/actions?query=workflow%3ARelease) and [PyPI](https://pypi.org/project/manubot/#history) for successful deployment of the release.

manubot/process/header-includes-template.html

@@ -1,6 +1,6 @@
 <!--
 Manubot generated metadata rendered from header-includes-template.html.
-Suggest improvements at https://github.com/manubot/manubot/blob/master/manubot/process/header-includes-template.html
+Suggest improvements at https://github.com/manubot/manubot/blob/main/manubot/process/header-includes-template.html
 -->
 <meta name="dc.format" content="text/html" />
 {% if pandoc.title is defined -%}