tests: Update month name check for Lithuanian locale

Update the abbreviated month name in the test to match the GNU libc
translation, coming from CLDR.

Fixes #1562
10 jobs for <span class="ref-name">issue-1562</span> in 14 minutes and 41 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #116490
cross-android_api21_arm64

00:00:59

passed #116491
cross-android_api28_arm64

00:01:11

passed #116492
cross-mingw64

00:01:50

passed #116489
fedora-autotools-x86_64

00:04:51

passed #116507
fedora-x86_64

00:05:55

manual #116495
freebsd-11 allowed to fail manual
freebsd-11-x86_64
passed #116493
win32
msys2-mingw32

00:07:23

passed #116494
win32
vs2017-x64

00:07:36

failed #116488
fedora-x86_64

00:09:31

 
  Coverage
passed #116496
coverage

00:01:08

74.9%