rename default branch in files

.github/workflows/build.yaml

@@ -2,7 +2,7 @@ name: Build
 on:
   push:
     branches:
-      - master
+      - main
       - '*.x'
     tags:
       - '*'

.github/workflows/tests.yaml

@@ -2,15 +2,15 @@ name: Tests
 on:
   push:
     branches:
-      - master
+      - main
       - '*.x'
     paths-ignore:
       - 'docs/**'
       - '*.md'
       - '*.rst'
   pull_request:
     branches:
-      - master
+      - main
       - '*.x'
     paths-ignore:
       - 'docs/**'

CONTRIBUTING.rst

@@ -141,12 +141,12 @@ Start coding
         $ git checkout -b your-branch-name origin/1.0.x
 
     If you're submitting a feature addition or change, branch off of the
-    "master" branch.
+    "main" branch.
 
     .. code-block:: text
 
         $ git fetch origin
-        $ git checkout -b your-branch-name origin/master
+        $ git checkout -b your-branch-name origin/main
 
 -   Using your favorite editor, make your changes,
     `committing as you go`_.