Bump deprecation markers.
Review Request #14982 — Created March 31, 2026 and submitted — Latest diff uploaded
We've decided to make what's currently in development as "Djblets 5.3"
be "Djblets 6.0", but we're not going to include any current deprecation
removals. This change bumps all markers in the code to be the next
version, and fixes up a couple typos I discovered along the way.
Ran unit tests.