X509.RDNSequence.get_attr fails when rdnSequence has charlist values

[hrivks]

First off, appreciate your effort into this package.

This is something I ran into when testing it on a bunch of different sample PEM files. All other sample PEM files worked expect this one. The sample PEM cert can be download from http://fm4dd.com/openssl/certexamples.htm

cert_text = """
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
"""

cert =  X509.Certificate.from_pem!(cert_text)
subject = X509.Certificate.subject(cert)
subject_string = X509.RDNSequence.to_string(subject)

results in error

** (FunctionClauseError) no function clause matching in List.to_string/1

    The following arguments were given to List.to_string/1:

        # 1
        {:printableString, 'Tokyo'}

    Attempted function clauses (showing 1 out of 1):

        def to_string(list) when is_list(list)

    (elixir) lib/list.ex:883: List.to_string/1
    (x509) lib/x509/rdn_sequence.ex:252: X509.RDNSequence.attr_to_string/1
    (elixir) lib/enum.ex:1327: Enum."-map/2-lists^map/1-0-"/2
    (elixir) lib/enum.ex:1327: Enum."-map/2-lists^map/1-0-"/2
    (x509) lib/x509/rdn_sequence.ex:154: X509.RDNSequence.to_string/1

I'm on Erlang/OTP 21 [erts-10.2.3]

[voltone]

Thanks for the report!