sslutil: support TLSV1_ALERT_PROTOCOL_VERSION reason code
It looks like python 3.10 returns a different reason code on protocol
version mismatch.
Differential Revision: https://phab.mercurial-scm.org/D12491
= Mercurial XXX =
== New Features ==
== Default Format Change ==
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== New Experimental Features ==
== Bug Fixes ==
== Backwards Compatibility Changes ==
== Internal API Changes ==
== Miscellaneous ==