Bump dependencies to their latest versions

[deining]

This PR bumps dependencies to their latest versions.

[chalin]

Thank you for the updates.

I can confirm that the UG generates as expected (only one surprise additionally generated </p> closing tag, but that seems valid):

$ (cd public && git diff -bw --ignore-blank-lines -I 'Hugo 0.12' -I 'meta name="twitter:|meta property="og:image"|meta itemprop="image"') | grep ^diff | head | grep -Ev '_print|\.xml$'
diff --git a/docs/adding-content/feedback/index.html b/docs/adding-content/feedback/index.html
diff --git a/docs/get-started/docsy-as-module/installation-prerequisites/index.html b/docs/get-started/docsy-as-module/installation-prerequisites/index.html