Upgrade Docsy to 0.7.2

[chalin]

• Fixes Fix sidenav height and padding by updating Docsy #3157. For details and screenshots, see the issue comments
• Upgrades to Docsy 0.7.2
  • Fixes Right nav formatting problem when page has no TOC #1102
• Closes Upgrade to Hugo 0.120.4, which include security patch #3522 by superseding it -- since Docsy 0.7.2 requires Hugo 0.120.4

Preview: https://deploy-preview-3519--opentelemetry.netlify.app

$ (cd public && git diff -bw --ignore-blank-lines -I "Create child page" -I "foldable-nav" -- . ':(exclude)*.xml') | grep ^diff | grep -v site/index
diff --git a/scss/main.css b/scss/main.css
diff --git a/scss/main.css.map b/scss/main.css.map