s/master/main/g (#69)

Convert `master` to `main`.

Note that the repo reference in `.gitignore` is correct, as they've also
switched. The only reference to master left is in the StyleCop JSON
schema because it hasn't migrated.

.github/workflows/main.yml

@@ -4,10 +4,10 @@ on:
   workflow_dispatch: # Allow running the workflow manually from the GitHub UI
   pull_request:
     branches:
-      - master
+      - main
   push:
     branches:
-      - master
+      - main
   workflow_call: # Allow to be called from the release workflow
   schedule:
     - cron: '31 15 * * 0' # Run periodically to keep CodeQL database updated

.gitignore

@@ -1,7 +1,7 @@
 ## Ignore Visual Studio temporary files, build results, and
 ## files generated by popular Visual Studio add-ons.
 ##
-## Get latest from https://github.com/github/gitignore/blob/master/VisualStudio.gitignore
+## Get latest from https://github.com/github/gitignore/blob/main/VisualStudio.gitignore
 
 # User-specific files
 *.suo

version.json

@@ -2,7 +2,7 @@
   "$schema": "https://raw.githubusercontent.com/dotnet/Nerdbank.GitVersioning/main/src/NerdBank.GitVersioning/version.schema.json",
   "version": "0.1.0",
   "publicReleaseRefSpec": [
-    "^refs/heads/master$",
+    "^refs/heads/main$",
     "^refs/heads/v\\d+(?:\\.\\d+)?$"
   ],
   "cloudBuild": {