CBMC/CI: Bump disk space to 64G

Signed-off-by: Hanno Becker <beckphan@amazon.co.uk>

Author: hanno-becker

.github/workflows/cbmc.yml

@@ -26,7 +26,7 @@ jobs:
       name: CBMC (ML-DSA-${{ matrix.parameter_set }}${{ matrix.reduce_ram && ', REDUCE_RAM' || '' }})
       ec2_instance_type: c7g.4xlarge
       ec2_ami: ubuntu-latest (aarch64)
-      ec2_volume_size: 20
+      ec2_volume_size: 64
       compile_mode: native
       opt: no_opt
       lint: false