core-deps: Bump wpe to 1.8.0

Debian testing/sid, Latest fedora and Arch has their webkit built against wpe 1.8.0. And so using 1.6.0 in jhbuild conflicts with webkit when the system provided webkit is used

So bump libwpe and wpebackend-fdo to 1.8.0

This fixes build failure on link:

/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37: undefined reference to `wpe_fdo_initialize_shm'

links to release pages: https://wpewebkit.org/release/libwpe-1.8.0.html, https://wpewebkit.org/release/wpebackend-fdo-1.8.0.html