Enhance the weekly mutation workflow markdown

This adds a code block to the cargo mutants issue creator for the missed
mutations and prints the current version of cargo mutants being used so
any new versions can easily be tracked where or why there are new
mutations.

.github/workflows/cron-weekly-cargo-mutants.yml

@@ -22,13 +22,15 @@ jobs:
         run: |
           if [ -s mutants.out/missed.txt ]; then
             echo "New missed mutants found"
+            MUTANTS_VERSION=$(cargo mutants --version)
             gh issue create \
             --title "New Mutants Found" \
             --body "$(cat <<EOF
           Displaying up to the first 10 mutants:
-
+          \`\`\`
           $(head -n 10 mutants.out/missed.txt)
-
+          \`\`\`
+          Running cargo mutants version: ${MUTANTS_VERSION}
           For the complete list, please check the [mutants.out artifact](https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}).
           EOF
           )"