Declare last failing jobs of #18164 allow_failure

So that they can be updated by their devs at their own pace
in the coming weeks.

.gitlab-ci.yml

@@ -636,6 +636,7 @@ library:ci-coquelicot:
 
 library:ci-cross_crypto:
   extends: .ci-template
+  allow_failure: true # See https://github.com/coq/coq/pull/18164/
 
 library:ci-engine_bench:
   extends: .ci-template
@@ -657,6 +658,7 @@ library:ci-fiat_crypto:
   - plugin:ci-bignums
   - plugin:ci-rewriter
   timeout: 3h
+  allow_failure: true # See https://github.com/coq/coq/pull/18164/
 
 library:ci-fiat_crypto_legacy:
   extends: .ci-template-flambda
@@ -676,6 +678,7 @@ library:ci-fiat_crypto_ocaml:
   - library:ci-fiat_crypto
   artifacts:
     paths: [] # These artifacts would go over the size limit
+  allow_failure: true # See https://github.com/coq/coq/pull/18164/
 
 library:ci-flocq:
   extends: .ci-template-flambda
@@ -887,6 +890,7 @@ plugin:ci-equations_test:
 
 plugin:ci-fiat_parsers:
   extends: .ci-template
+  allow_failure: true # See https://github.com/coq/coq/pull/18164/
 
 plugin:ci-lean_importer:
   extends: .ci-template