Add IGNORE_DEPRECATIONS to make CI happy

As hinted by @ebassi:
GNOME/glib!1960 (comment 1101626)
10 jobs for source-attach-trigger-wakeup in 35 minutes and 1 second (queued for 1 second)
latest
Status Job ID Name Coverage
  Style Check
passed #1346381
check-todos

00:02:31

failed #1346380
allowed to fail
style-check-diff

00:01:13

 
  Build
passed #1346384
cross-android_api21_arm64

00:01:51

passed #1346385
cross-android_api28_arm64

00:01:57

passed #1346386
cross-mingw64

00:03:14

passed #1346383
debian-stable-x86_64

00:02:17

passed #1346382
fedora-x86_64

00:12:10

passed #1346387
win32-ps
msys2-mingw32

00:15:34

passed #1346388
win32-ps
vs2017-x64

00:08:46

 
  Coverage
passed #1346389
coverage

00:01:21

76.2%
 
Name Stage Failure
failed
style-check-diff Style Check
   wchar_t debugger_enough[G_N_ELEMENTS (not_enough) + 1];
char *debugger_enough_utf8;
- wchar_t debugger_big[65535] = {0};
+ wchar_t debugger_big[65535] = { 0 };
char *debugger_big_utf8;
gchar *output;
guintptr be = (guintptr) 0xFFFFFFFF;
Cleaning up file based variables
ERROR: Job failed: exit code 1