Upgrade transient dependency fast_gettext

What does this MR do and why?

This MR bump the version of the transient dependency fast_gettext to 2.3.0 by using bundle update fast_gettext.

This version contains a fix which reduces amount of reads of empty.mo for the default locale.

See https://github.com/grosser/fast_gettext/pull/138.

Closes #391840 (closed).

Gem diff

See https://my.diffend.io/gems/fast_gettext/2.1.0/2.3.0

How to set up and validate locally

From #391840 (closed).

$ echo $empty_mo
/home/peter/.dotfiles/asdf/installs/ruby/3.0.5/lib/ruby/gems/3.0.0/gems/fast_gettext-2.3.0/lib/fast_gettext/vendor/empty.mo

$ strace -qqq -f -e signal=none -e trace=openat -P $empty_mo bin/rails console
WARNING: This version of GitLab depends on gitlab-shell 14.17.0, but you're running 14.15.0. Please update gitlab-shell.
[pid 246242] openat(AT_FDCWD, "/home/peter/.dotfiles/asdf/installs/ruby/3.0.5/lib/ruby/gems/3.0.0/gems/fast_gettext-2.3.0/lib/fast_gettext/vendor/empty.mo", O_RDONLY|O_CLOEXEC) = 15
--------------------------------------------------------------------------------
 Ruby:         ruby 3.0.5p211 (2022-11-24 revision ba5cf0f7c5) [x86_64-linux]
 GitLab:       15.9.0-pre (9346f792763) EE
 GitLab Shell: 14.15.0
 PostgreSQL:   12.13
------------------------------------------------------------[ booted in 12.52s ]
Loading development environment (Rails 6.1.7.2)
[1] pry(main)> _('Hello')
=> "Hello"
[2] pry(main)>

fast_gettext loads empty.mo only once ✅

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