Failing test `toTitle_1stNotLower`

[Lysxia]

I can reproduce it reliably by just raising the number of random test cases:

cabal test --test-options="--quickcheck-tests 10000 -p toTitle_1"

         t_toTitle_1stNotLower: FAIL
            *** Failed! Falsified (after 1299 tests and 7 shrinks):
            "\4317"

My current hypothesis is that the generated file src/Data/Text/Internal/Fusion/CaseMapping.hs is outdated (Unicode 9) compared to what base uses (Unicode 12). Can't we reuse functionality in base, possibly adding whatever is missing to base?

(This was also mentioned in passing in #326 (comment))

[Bodigrim]

Regenerating case mapping would be nice, but it does not help in this case. See discussion at #302 (comment) One should exclude Georgian Extended chars from this test.