tomerl doesn't support older versions of Erlang.

.github/workflows/cicd.yml

@@ -45,7 +45,7 @@ jobs:
 
     strategy:
       matrix:
-        otp_version: ['21.3', '22.3', '23.3']
+        otp_version: ['23.3']
 
     steps:
     - uses: actions/checkout@v2

README.md

@@ -140,7 +140,7 @@ Copyright © 2020-2023, Duncan McGreggor <[email protected]>.
 [gh-actions]: https://github.com/lfex/bombadil/actions
 [lfe]: https://github.com/rvirding/lfe
 [lfe-badge]: https://img.shields.io/badge/lfe-2.1-blue.svg
-[erlang-badge]: https://img.shields.io/badge/erlang-20%20to%2025-blue.svg
+[erlang-badge]: https://img.shields.io/badge/erlang-23%20to%2026-blue.svg
 [versions]: https://github.com/lfex/bombadil/blob/master/.github/workflows/cicd.yml
 [github-tag]: https://github.com/lfex/bombadil/tags
 [github-tag-badge]: https://img.shields.io/github/tag/lfex/bombadil.svg