t_blockCode test failure again with ICU 74

This is a reprise of
- #94

Happens on macOS with [ICU 74](https://github.com/haskell/text-icu/actions/runs/8943327460/job/24567789387#step:9:13):
https://github.com/haskell/text-icu/actions/runs/8943327460/job/24567789387#step:12:636
```
t_blockCode: [Failed]
*** Failed! (after 25 tests):
Exception:
toEnum{BlockCode}: tag (328) is outside of enumeration's range (0,327)
CallStack (from HasCallStack):
error, called at Data/Text/ICU/Char.hsc:495:17 in text-icu-0.8.0.5-FtrCGOmY2PD7vvbWpyQUDD:Data.Text.ICU.Char
'\191897'
```

Update: also fails on Windows with [ICU 74.2](https://github.com/haskell/text-icu/actions/runs/8943757763/job/24569171067#step:5:7):
https://github.com/haskell/text-icu/actions/runs/8943757763/job/24569171067#step:11:26
```
*** Failed! (after 13 tests):
Exception:
toEnum{BlockCode}: tag (328) is outside of enumeration's range (0,327)
CallStack (from HasCallStack):
error, called at Data\Text\ICU\Char.hsc:495:17 in text-icu-0.8.0.5-inplace:Data.Text.ICU.Char
'\191528'
```

Start with the failing t_blockCode test and Data/Text/ICU/Char.hsc around line 495, then compare the macOS and Windows ICU 74 CI failures linked in the issue. Reproduce with ICU 74 if possible and verify that the test no longer raises the out-of-range BlockCode exception while preserving behavior on supported ICU versions.

Written by the indexing model from the issue text.