Fix ArchiveTimestampSequence definition

[arkkors]

RFC4998, Section 5.1 defines the ArchiveTimestampSequence as:

ArchiveTimeStampChain    ::= SEQUENCE OF ArchiveTimeStamp
ArchiveTimeStampSequence ::= SEQUENCE OF ArchiveTimeStampChain

asn1crypto.tsp defines ArchiveTimeStampSequence as:

class ArchiveTimeStampSequence(SequenceOf):
   _child_spec = ArchiveTimeStamp

and ArchiveTimeStampChain is absent.

This MR fixes the issue.

[wbond]

Thanks for catching this.

Do you have an example file we could add as a fixture to test this with?

[wbond]

Pinging you @arkkors to see if you have a test file we could use for this?

[arkkors]

Sorry, lost track of that.

I myself don't have test files right now. However there is this repo here: https://github.com/de-bund-bsi-tr-esor/ERVerifyTool
In particular this file looks usable: https://github.com/de-bund-bsi-tr-esor/ERVerifyTool/blob/master/test/1.RFC4998-bin-data_er/BIN_ER.ers

Does that work?