Set up Dependabot RBI updates

.github/workflows/dependabot_update_rbis.yml

@@ -0,0 +1,57 @@
+name: Update gem RBIs on Dependabot PRs
+
+on: workflow_call
+
+permissions:
+  contents: write
+  pull-requests: write
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref }}
+  cancel-in-progress: true
+
+jobs:
+  update-gem-rbis:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    if: ${{ github.actor == '"dependabot[bot]"' }}
+    steps:
+      - name: Checkout PR branch
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+      - name: Get Ruby version from dev.yml
+        id: ruby
+        shell: ruby -ryaml {0}
+        run: |
+          exit 1 unless File.exist?("dev.yml")
+          yaml = YAML.respond_to?(:unsafe_load_file) ? YAML.unsafe_load_file("dev.yml") : YAML.load_file("dev.yml")
+          ruby_version = yaml["up"]
+            &.find {|h| Hash === h && h.key?("ruby") }
+            &.dig("ruby")
+            .then {|c| Hash === c ? c["version"] : c }
+          exit 1 unless ruby_version
+          File.write(ENV.fetch("GITHUB_OUTPUT"), "ruby_version=#{ruby_version}\n", mode: "a")
+      - uses: ruby/setup-ruby@v1
+        id: setup
+        with:
+          bundler-cache: true
+          ruby-version: ${{ steps.ruby.outputs.version }}
+      - name: Update gem RBIs
+        run: |
+          bin/tapioca gem
+      - name: Check for modified files
+        id: git_modified_files_check
+        # If there are changes in the sorbet directory, `echo -n` will return true (zero exit code)
+        run: |
+          status=$(git status sorbet --porcelain=v1)
+          echo "changes=$([ -n "$status" ]; echo $?)" >> $GITHUB_OUTPUT
+      - name: Push changes
+        if: ${{ steps.git_modified_files_check.outputs.changes == 0 }}
+        run: |
+          git config user.name github-actions
+          git config user.email [email protected]
+          git add sorbet/*
+          date="$(date -u +"%Y-%m-%d")"
+          git commit -m "Update RBI files for gems ${date} [dependabot skip]"
+          git push

.github/workflows/dependabot_update_rbis_run.yml

@@ -0,0 +1,6 @@
+name: Update gem RBIs on Dependabot PRs
+on: [pull_request]
+
+jobs:
+  dependabot_update_rbis:
+    uses: Shopify/ruby-lsp/.github/workflows/dependabot_update_rbis.yml@main

sorbet/tapioca/config.yml

@@ -3,8 +3,9 @@ gem:
     "psych": "false"
   # Add your `gem` command parameters here:
   #
-  # exclude:
-  # - gem_name
+  # rdoc causes a failure 'webrick is not found.' when running `tapioca gem`.
+  exclude:
+  - rdoc
   # doc: true
   # workers: 5
 dsl: