t_toUpper_char fails on s390x

[Bodigrim]

https://github.com/haskell/text/actions/runs/9628836664/job/26557513845 failed with

             t_toUpper_char:                            FAIL (0.02s)
              *** Failed! Falsified (after 80 tests):
              '\42954'
              "\42953" /= "\42954"
              Use --quickcheck-replay=567863 to reproduce.

I have not looked into it, just filing.

[Bodigrim]

Letters in question:

• Latin Capital Letter S with Short Stroke Overlay
• Latin Small Letter S with Short Stroke Overlay

[Lysxia]

The failing test t_toUpper_char is guarded by a MIN_VERSION_base(...) condition which goes out of date almost every time we upgrade the Unicode version for the case mappings in text.

• GHC 8.8/base 4.13 (what is available in the s390x runner) uses Unicode 12.0
• Those two characters in the failing test case are from Unicode 13.0
• (for the record, text is currently at Unicode 15.0)

[wismill]

Related: haskell/core-libraries-committee#278