Disable afl for gnupg (#5854)

diff --git a/projects/gnupg/project.yaml b/projects/gnupg/project.yaml
index c2c6ab2..516132e 100644
--- a/projects/gnupg/project.yaml
+++ b/projects/gnupg/project.yaml
@@ -2,3 +2,6 @@
 language: c++
 primary_contact: "p.antoine@catenacyber.fr"
 main_repo: 'git://git.gnupg.org/gnupg.git'
+fuzzing_engines:
+  - libfuzzer
+  - honggfuzz