ci : check that pre-tokenizer hashes are up-to-date (#15032)

* torch is not required for convert_hf_to_gguf_update

* add --check-missing parameter

* check that pre-tokenizer hashes are up-to-date

requirements/requirements-convert_hf_to_gguf_update.txt

@@ -1,7 +1 @@
 -r ./requirements-convert_legacy_llama.txt
---extra-index-url https://download.pytorch.org/whl/cpu
-torch~=2.2.1; platform_machine != "s390x"
-
-# torch s390x packages can only be found from nightly builds
---extra-index-url https://download.pytorch.org/whl/nightly
-torch>=0.0.0.dev0; platform_machine == "s390x"