Generating keys in FIPS mode results in a crash

@jjelen reported the following:

There might be more possible issues in FIPS mode, as we got stuck on generating the key already.

Reproducer and logs in FIPS mode:

# sq key generate --new-password-file passwd --userid fipsuser --own-key
thread 'main' panicked at /builddir/build/BUILD/sequoia-sq-1.3.0/vendor/sequoia-openpgp/src/crypto/mem.rs:408:41:
called `Result::unwrap()` on an `Err` value: Custom { kind: Other, error: error:0308010C:digital envelope routines:inner_evp_generic_fetch:unsupported:crypto/evp/evp_fetch.c:355:Global default library context, Algorithm (AES-256-OCB : 0), Properties () }