package/libcurl: bump version to 7.88.1

Bugfix release fixing a number of issues introduced in 7.88.0:

https://curl.se/changes.html#7_88_1
https://daniel.haxx.se/blog/2023/02/20/7-88-1-the-second-final-one/



Signed-off-by: Peter Korsgaard <peter@korsgaard.com>