Update to pdfjs 2.10.377 to fix the preview with firefox 68

The previous release had some regex features in the legacy build
that resulted in a syntax error with firefox 68.

To be exact this:
new RegExp("([\\p{N}\\p{L}\\p{M}]+)|([^\\p{N}\\p{L}\\p{M}]+)", "gu")

which is only supported since firefox 78:
https://caniuse.com/mdn-javascript_builtins_regexp_property_escapes