Revert hack for coq 8.14 compilation.

Related issues:
- https://github.com/coq/coq/issues/15044 (bug report),
- https://github.com/ocaml/opam-repository/pull/19808 (package fix).
1 job for master in 9 minutes and 3 seconds (queued for 7 seconds)
Name Stage Failure
failed
trigger-iris.dev Build
ubase                    0.04        Remove diacritics from latin utf8 strings
uchar 0.0.2 Compatibility library for OCaml's Uchar module
uutf 1.0.2 Non-blocking streaming Unicode codec for OCaml
yojson 1.7.0 Yojson is an optimized parsing and printing library for the JSON format
z3 4.8.11 Z3 solver
zarith 1.12 Implements arithmetic and logical operations over arbitrary-precision integers
'opam upgrade builddep/ coq coq-stdpp.dev coq-iris.dev cerberus' failed
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1