fix getMaxSCOLength to take into account MQSCO_VERSION_7

[louissobel]

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What

Updated getMaxSCOLength to take MQSCO_VERSION_7 into account

How

This is a bug: freeHTTPSKeyStore tries to free this data, but because the C SCO structure isn't big enough, it tries to free memory from outside the structure

Testing

I did not test this.

Issues

Links to the github issue(s) (if present) that this pull request is resolving.

[ibmmqmet]

Thanks for finding this. I've added a check to the release process so this kind of error won't happen again.