fix: change check for optimization to compare commits

    ### ----- run pytest for merge target now -----

    # create float reference outputs with corresponding branch

    # optimization: for MRs with no parallel branch in float, REF_[ENCODER|DECODER]_PATH and MERGE_SOURCE_FLOAT_REF_[ENCODER|DECODER]_PATH are the same (see wiki: https://forge.3gpp.org/rep/sa4/audio/ivas-basop/-/wikis/CI-Environment#how-are-regressions-calculated).

    # optimization: for MRs with no parallel branch in float, FLOAT_REF_COMMIT and MERGE_SOURCE_FLOAT_REF_COMMIT are the same (see wiki: https://forge.3gpp.org/rep/sa4/audio/ivas-basop/-/wikis/CI-Environment#how-are-regressions-calculated).

    #               Hence, we only need to do a second reference creation run if the paths are distinct as the result would be the same otherwise. This saves time for branches with no parallel branch in float.

    - |

      if [ $REF_ENCODER_PATH != $MERGE_SOURCE_FLOAT_REF_ENCODER_PATH ] || [ $REF_DECODER_PATH != $MERGE_SOURCE_FLOAT_REF_DECODER_PATH ]; then

      if [ $FLOAT_REF_COMMIT != $MERGE_SOURCE_FLOAT_REF_COMMIT ]; then

        python3 -m pytest $TEST_SUITE --update_ref 1 $enc_stats_arg $enc_dmx_arg --create_ref -n auto --ref_encoder_path $REF_ENCODER_PATH --ref_decoder_path $REF_DECODER_PATH || exit_code=$?

      fi

    - bash "${CI_PROJECT_DIR}"/ivas-codec-ci/snippets/basop/overwrite-pytest-cache-with-artifact.sh