gtksourceview3: update to 3.24.11.

News in 3.24.11, 2019-05-05
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* Improvements to the syntax highlighting of: YAML, Julia, C++,  and C.
* Fixes to GObject Introspection annotations.
* Fix a crash with YAML.
* Fix a crash in presense of Byte-Order-Markers.

News in 3.24.10, 2019-03-15
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* New syntax highlighting definition file for: Powershell
* Improvements to the syntax highlighting of: reStructuredText, C++,
  CSS, HTML, Groovy, Meson, Python3, and Logtalk.
* Fix testsuite for changes in GLib hashtable ordering.
* Avoid double entry of languages based on globs.
* MSVC build improvements.
* Fix usage of GRegex for offset in text, which fixes a Valgrind warning.
* Ensure CSS is inherted from parent style schemes.
* Avoid storing GtkTextIter across main-loop boundaries.
* Fix incorrect transfer annoation for gtk_source_buffer_create_source_mark().
* Various memory leak fixes.
* Translation updates.

(wiz)