AssertionError when run Quickstart in local envrionment

[Opdoop]

Envrionment

• fibber version: 0.3.1
• Python version: 3.6.9
• Operating System: Ubuntu 18.04.5 LTS

Description

Run Quickstart (3) Create a Fibber object.
Meet this bug:

`Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "/usr/local/lib/python3.6/dist-packages/fibber/fibber.py", line 67, in __init__
    self._strategy.fit(trainset)
  File "/usr/local/lib/python3.6/dist-packages/fibber/paraphrase_strategies/asrs_strategy.py", line 296, in fit
    self._strategy_config["sim_metric"])
  File "/usr/local/lib/python3.6/dist-packages/fibber/metrics/metric_utils.py", line 99, in get_metric
    assert metric_name in self._metrics
AssertionError

Compared with code in Colab, I think this is caused by pass "asrs_sim_metric": "CESimilarityMetric" in arg_dict.
After delete "asrs_sim_metric": "CESimilarityMetric" in arg_dict. The bug goes away and gets the same result shown in (4) You can also ask fibber to paraphrase your sentence.
Currently, I don't know whether it's necessary to pass asrs_sim_metric. Should we remove "asrs_sim_metric": "CESimilarityMetric"?

[Opdoop]

According to asrs_strategy, CESimilarityMetric is default value of sim_metric. So I think we could omit this asrs_sim_metric.

fibber/fibber/paraphrase_strategies/asrs_strategy.py

Line 281 in ac278a0

("sim_metric", str, "CESimilarityMetric", "similarity metric")