Update Flatpak platform to 9.1

[ryonakano]

Requires elementary/default-settings#372 to run
Based on #188

Checklists

• The app launches on Early Access (x86_64)
• Can browse our website (https://elementary.io)

[ryonakano]

Hmm Epiphany 48.5 fails to build with our runtime which is based on GNOME runtime 51. It looks like there was an API breaking change with nettle_hkdf_extract()? 🤔

FAILED: [code=1] lib/sync/libephysync.so.p/ephy-sync-crypto.c.o 
/usr/bin/ccache cc -Ilib/sync/libephysync.so.p -Ilib/sync -I../lib/sync -Ilib -I../lib -I../lib/history -I. -I.. -I../lib/sync/debug -I../lib/contrib -I/usr/include/cairo -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/harfbuzz -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/sysprof-6 -I/usr/include/pixman-1 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/glycin-2 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/gio-unix-2.0 -I/usr/include/gsettings-desktop-schemas -I/usr/include/gtk-4.0 -I/usr/include/pango-1.0 -I/usr/include/fribidi -I/usr/include/graphene-1.0 -I/usr/lib/x86_64-linux-gnu/graphene-1.0/include -I/usr/include/json-glib-1.0 -I/usr/include/libadwaita-1 -I/usr/include/ministream -I/usr/include/libsecret-1 -I/usr/include/x86_64-linux-gnu -I/usr/include/libsoup-3.0 -I/usr/include/libxml2 -I/usr/include/webkitgtk-6.0 -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wextra -std=gnu11 -O0 -g -Werror=declaration-after-statement -Werror=implicit-function-declaration -Wno-cast-function-type -Wno-missing-field-initializers -Wno-unused-parameter -O2 -pipe -g -Wp,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -fPIC -mfpmath=sse -msse -msse2 -pthread -mfpmath=sse -msse -msse2 -mfpmath=sse -msse -msse2 -mfpmath=sse -msse -msse2 -DWITH_GZFILEOP -MD -MQ lib/sync/libephysync.so.p/ephy-sync-crypto.c.o -MF lib/sync/libephysync.so.p/ephy-sync-crypto.c.o.d -o lib/sync/libephysync.so.p/ephy-sync-crypto.c.o -c ../lib/sync/ephy-sync-crypto.c
../lib/sync/ephy-sync-crypto.c: In function ‘ephy_sync_crypto_hkdf’:
../lib/sync/ephy-sync-crypto.c:555:17: error: passing argument 5 of ‘nettle_hkdf_extract’ makes pointer from integer without a cast [-Wint-conversion]
  555 |                 in_len, in, prk);
      |                 ^~~~~~
      |                 |
      |                 gsize {aka long unsigned int}
In file included from ../lib/sync/ephy-sync-crypto.c:33:
/usr/include/nettle/hkdf.h:51:49: note: expected ‘const uint8_t *’ {aka ‘const unsigned char *’} but argument is of type ‘gsize’ {aka ‘long unsigned int’}
   51 |              size_t secret_size, const uint8_t *secret,
      |                                  ~~~~~~~~~~~~~~~^~~~~~
../lib/sync/ephy-sync-crypto.c:555:25: warning: passing argument 6 of ‘nettle_hkdf_extract’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
  555 |                 in_len, in, prk);
      |                         ^~
/usr/include/nettle/hkdf.h:52:23: note: expected ‘uint8_t *’ {aka ‘unsigned char *’} but argument is of type ‘const guint8 *’ {aka ‘const unsigned char *’}
   52 |              uint8_t *dst);
      |              ~~~~~~~~~^~~
../lib/sync/ephy-sync-crypto.c:551:3: error: too many arguments to function ‘nettle_hkdf_extract’; expected 6, have 7
  551 |   hkdf_extract (&ctx,
      |   ^~~~~~~~~~~~
/usr/include/nettle/hkdf.h:48:1: note: declared here
   48 | hkdf_extract(void *mac_ctx,
      | ^~~~~~~~~~~~
[59/451] Compiling C object lib/sync/libephysync.so.p/ephy-password-record.c.o
[60/451] Compiling C object lib/sync/libephysync.so.p/ephy-password-manager.c.o
[61/451] Compiling C object lib/sync/libephysync.so.p/ephy-sync-service.c.o
ninja: build stopped: subcommand failed.
Error: module epiphany: Child process exited with code 1

[ryonakano]

Trying whether build succeeds when latest Epiphany (51.0).

[ryonakano]

OK build succeeds, so we first need to bump the ancient version of Epiphany before this……

#188