build: move pr_commits fetch before pr_author_emails computation in generate_pr_commit_message

The `pr_author_emails` list referenced `$pr_commits` to extract commit
author emails, but `pr_commits` was fetched afterwards, causing the
variable to be empty. This resulted in PR authors being incorrectly
added to the "Co-authored-by" trailer when their commit email didn't
match their GitHub noreply address.

---
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/scripts/generate_pr_commit_message

@@ -153,6 +153,9 @@ main() {
 	# Resolve the PR author's name and email using .mailmap:
 	pr_author_resolved=$(resolve_user "$pr_author_login")
 
+	# Fetch commits in the PR:
+	pr_commits=$(github_api "GET" "/repos/$REPO_OWNER/$REPO_NAME/pulls/$pr_number/commits")
+
 	pr_author_id=$(echo "$pr_details" | jq -r '.user.id')
 	pr_author_emails=$(
 	{
@@ -181,9 +184,6 @@ main() {
 	pr_reviews=$(github_api "GET" "/repos/$REPO_OWNER/$REPO_NAME/pulls/$pr_number/reviews")
 	reviewers=$(echo "$pr_reviews" | jq -r '.[] | select(.state == "APPROVED" ) | .user.login' | sort -u)
 
-	# Fetch commits in the PR:
-	pr_commits=$(github_api "GET" "/repos/$REPO_OWNER/$REPO_NAME/pulls/$pr_number/commits")
-
 	# Extract co-authors from commit messages:
 	co_authors=$(echo "$pr_commits" | jq -r '.[].commit.message' | grep -Eio 'Co-authored-by:.*' | sort -u)
 	processed_co_authors=""