Update workflows for branch name 'main'

Author: borchero

.github/workflows/docs.yaml

@@ -4,10 +4,10 @@ on:
     types: [published]
   push:
     branches:
-      - master
+      - main
   pull_request:
     branches:
-      - master
+      - main
 
 jobs:
   build:

.github/workflows/style.yaml

@@ -2,10 +2,10 @@ name: Check Code Style
 on:
   push:
     branches:
-      - master
+      - main
   pull_request:
     branches:
-      - master
+      - main
 
 jobs:
   run-black:

.github/workflows/tests.yaml

@@ -2,10 +2,10 @@ name: Run Tests
 on:
   push:
     branches:
-      - master
+      - main
   pull_request:
     branches:
-      - master
+      - main
 
 jobs:
   run-tests:

README.md

@@ -112,4 +112,4 @@ Currently, PyCave implements three different models:
 
 ## License
 
-PyCave is licensed under the [MIT License](https://github.com/borchero/pycave/blob/master/LICENSE).
+PyCave is licensed under the [MIT License](https://github.com/borchero/pycave/blob/main/LICENSE).