package/enchant: bump to version 2.2.8

- Update site to get latest version
- Update hash of COPYING.LIB (update in FSF address with
  https://github.com/AbiWord/enchant/commit/adcb08292d4650a1c258f9b02c53cf1e26b47185

)
- Update indentation in hash file (two spaces)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>