Bump asciidoctor from 2.0.14 to 2.0.20

Bumps [asciidoctor](https://github.com/asciidoctor/asciidoctor) from 2.0.14 to 2.0.20.
- [Release notes](https://github.com/asciidoctor/asciidoctor/releases)
- [Changelog](https://github.com/asciidoctor/asciidoctor/blob/main/CHANGELOG.adoc)
- [Commits](asciidoctor/asciidoctor@v2.0.14...v2.0.20)

---
updated-dependencies:
- dependency-name: asciidoctor
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -1,7 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    asciidoctor (2.0.14)
+    asciidoctor (2.0.20)
 
 PLATFORMS
   ruby