deps: update golang.org/x/text to 0.3.6

[jseldess]

PR: cockroachdb/cockroach#64695

From release notes:

Collated strings may now have a locale that is a language tag, followed by a -u- suffix, followed by anything else. For example, any locale with a prefix of en-US-u- is now considered valid. [#64695][#64695] {% comment %}doc{% endcomment %}

[ericharmeling]

We don't need to explicitly document this beyond what was documented in #8523.