build: use heredoc format to preserve LaTeX escapes in PR coverage comments

---
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/publish_coverage_pr.yml

@@ -67,9 +67,12 @@ jobs:
         if: steps.download-metadata.outcome == 'success'
         run: |
           pr_number=$(cat pr-metadata/pr_number)
-          report=$(cat pr-metadata/report)
           echo "pr_number=$pr_number" >> $GITHUB_OUTPUT
-          echo "report=$report" >> $GITHUB_OUTPUT
+          {
+            echo 'report<<EOF'
+            cat pr-metadata/report
+            echo 'EOF'
+          } >> $GITHUB_OUTPUT
 
       # Post report as comment to PR:
       - name: 'Post report as comment to PR'