Log Message:
Update gtksourceview4 to 4.8.0

- fix introspection option

News in 4.8.0, 2020-09-12
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* Translation updates

News in 4.7.90, 2020-08-07
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* Bump GTK requirement to 3.24 for gdk_window_move_to_rect()
* Use gdk_window_move_to_rect() to more reliably position completion windows
* erb.lang: initial support for ERB
* javascript.lang, typescript.lang: various correctness and performance
  improvements.
* Translation updates

News in 4.6.1, 2020-06-26
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* Fix various G-I annotations
* Improve draw-spaces coloring in solarized-light
* javascript.lang: Performance improvements
* c.lang: Fixes for #include preprocessor
* sql.lang: Language completeness improvements
* latex.lang: additional keywords
* sh.lang: improved parameter expansion
* yara.lang: initial support for YARA
* Translation updates