moreText in Excerpt block isn't internationalised

[iamtakashi]

For example,
<!-- wp:post-excerpt {"moreText":"— read more","showMoreOnNewLine":false} /-->

That text for the more text, — read more should be internationalised when the theme is saved with CBT.

[t-hamano]

Thanks for the report. Let me close this issue as part of #776.