stat/locales: Fix fluent_linter errors

[drinkcat]

Arguably this should be part of the CI, but I'm not sure how to run it outside of precommit.

[sylvestre]

i have a patch for flt check in github, easy :)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/misc/tee (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)

[sylvestre]

Are you sure they are really issues?

[drinkcat]

I... don't know, I happened to touch another ftl file and this popped up:

$ git checkout upstream/main 
$ sed -i -e 's/about/above/' src/uu/stat/locales/en-US.ftl
$ git commit -a
...
fluent_linter............................................................Failed
- hook id: fluent_linter
- exit code: 1

Files to analyze: 199.

            File path: src/uu/stat/locales/en-US.ftl
            Message ID: -
            Position: line 56 column 1
            Error (GC02): Group comments (##) should be followed by one empty line.

            File path: src/uu/stat/locales/en-US.ftl
            Message ID: -
            Position: line 66 column 1
            Error (GC02): Group comments (##) should be followed by one empty line.
...