libical: Update to 3.0.7

Version 3.0.7 is a patch release.
This release is binary and source compatible with version 3.0.0.
Note that the libical-glib library is considered unstable; therefore not binary compatible with previous releases

Release Notes:

    libical-glib: Fix ICalAttach handling of the icalattach native structure
    Let icalattach_new_from_data() use the 'free_fn' argument again
    Fix memory leaks in attachment handling and elsewhere
    Fix a multithreading race condition
    More fuzzification fixes

(nia)