Commit a874ba8 includes instances of ⎕ucs 8212 (Em-dash) which cannot be brought into Classic interpreters

[dyaandys]

⎕ucs 8212 has been added to HttpCommand.dyalog line 1105 (in parseSSE) which prevents the user command being ]loaded in classic interpreters.

One has been added to sse.md line 1 too, but that is not included in the release, so can be left as is.