fix import warning

Author: LangQi99

lib/matplotlib/backends/backend_gtk3.py

@@ -18,6 +18,8 @@
     # :raises ValueError: If module/version is already loaded, already
     # required, or unavailable.
     gi.require_version("Gtk", "3.0")
+    # Also require GioUnix to avoid PyGIWarning when Gio is imported
+    gi.require_version("GioUnix", "2.0")
 except ValueError as e:
     # in this case we want to re-raise as ImportError so the
     # auto-backend selection logic correctly skips.

lib/matplotlib/backends/backend_gtk4.py

@@ -17,6 +17,8 @@
     # :raises ValueError: If module/version is already loaded, already
     # required, or unavailable.
     gi.require_version("Gtk", "4.0")
+    # Also require GioUnix to avoid PyGIWarning when Gio is imported
+    gi.require_version("GioUnix", "2.0")
 except ValueError as e:
     # in this case we want to re-raise as ImportError so the
     # auto-backend selection logic correctly skips.