TestRIG: don't fuzz the A extension

This will result in near instant divergences until
CTSRD-CHERI/qemu#208 is merged.

pycheribuild/projects/testrig.py

@@ -251,7 +251,8 @@ class _TestRigQEMURV64Base:
     dependencies = (*RunTestRIGBase.dependencies, "sail-cheri-riscv", "qemu")
     # NB: can't use GC here since that implicitly enables ihpm in QCVengine and QEMU does not support mcountinhibit
     # util we have updated to b1675eeb3e6e38b042a23a9647559c9c548c733d.
-    verification_archstring = "rv64imafdc_s_xcheri_zicsr_zifencei"
+    # TODO: enable A again once https://github.com/CTSRD-CHERI/qemu/pull/208 is merged.
+    verification_archstring = "rv64imfdc_s_xcheri_zicsr_zifencei"
 
     def get_reference_implementation_command(self, port: int) -> "list[str]":
         assert isinstance(self, RunTestRIGBase)