Migrate away from standardrb-action

Because Andrew told us to:

> This action is unnecessary and will slow down your CI suite. As such, it is not actively maintained.
> https://github.com/andrewmcodes/standardrb-action?tab=readme-ov-file

.github/workflows/standardrb.yml

@@ -3,11 +3,12 @@ name: StandardRB
 on: [push]
 
 jobs:
-  build:
+  standardrb:
+    name: StandardRB
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v1
-    - name: StandardRB Linter
-      uses: andrewmcodes/[email protected]
-      env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+      - run: bundle exec standardrb --format github --parallel