unable to run PVS 6.0 after applying security update to macOS 10.15.7

[kiniry]

I applied Apple's security update last night and now even PVS 6 will not run successfully. In particular, performing a change-context results in the following *Error Output*:

Error: `<CE test>' is not of the expected type `sequence'

The end of *Messages* is:

Loading /usr/local/pvs/emacs/emacs-src/prooflite.el (source)...done
Loading newcomment...done
../../usr/local/pvs/emacs/emacs-src/pvs-load.el: (lambda (dir) ...) quoted with ' rather than with #'
Initializing PVS: please wait...
Started initializing ILISP
Finished initializing pvsallegro
Context changed to /Users/kiniry/
Ready
Loading /usr/local/pvs/emacs/emacs-src/pvs-load.el (source)...done
Package cl is deprecated
SPC-scroll, I-ignore, K-keep, A-abort sends and keep or B-break: 
Abort pending commands and keep in *Errors*

The *pvs* buffer is hung.