build: ensure workflow does not fail for non-zero exit codes

#3106 introduced a non-zero exit
code for the `.github/workflows/scripts/generate_pr_commit_message`
script whenever the PR references a tracking issue. This caused the
workflow to fail for all such PRs due to GitHub Actions running shell
scripts using bash -e {0}, causing the script to exit immediately
if any command exits with a non-zero status.

---
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: na
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

Author: Planeshifter

.github/workflows/generate_pr_commit_message.yml

@@ -65,6 +65,7 @@ jobs:
       # Generate commit message:
       - name: 'Generate commit message'
         id: commit_message
+        shell: bash {0} # Omit -e to avoid triggering a failure if the script returns a non-zero exit code
         run: |
           COMMIT_MESSAGE=$($GITHUB_WORKSPACE/.github/workflows/scripts/generate_pr_commit_message $PR_NUMBER)
           EXIT_CODE=$?