build: add dry-run option and GH_TOKEN env var to merge_ready_prs workflow

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: na
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: na
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: na
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: passed
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

Author: Planeshifter

.github/workflows/merge_ready_prs.yml

@@ -22,6 +22,11 @@ name: merge_ready_prs
 # Workflow triggers:
 on:
   workflow_dispatch:
+    inputs:
+      dry-run:
+        description: 'Dry run (only print PRs to be merged)'
+        type: boolean
+        default: false
 
 # Workflow jobs:
 jobs:
@@ -45,6 +50,7 @@ jobs:
       # Merge PRs with Ready to Merge label:
       - name: 'Merge PRs'
         env:
+          GH_TOKEN: ${{ secrets.STDLIB_BOT_GITHUB_TOKEN }}
           GITHUB_TOKEN: ${{ secrets.STDLIB_BOT_GITHUB_TOKEN }}
         run: |
           # Get all PRs with the "Ready to Merge" label:
@@ -58,6 +64,15 @@ jobs:
           echo "Found PRs to merge: $prs"
           echo ""
 
+          # If dry run, just print the PRs and exit:
+          if [ "${{ inputs.dry-run }}" == "true" ]; then
+            echo "Dry run mode. PRs that would be merged:"
+            for pr in $prs; do
+              echo "  - PR #$pr"
+            done
+            exit 0
+          fi
+
           # Track results:
           succeeded=""
           failed=""