I am uploading a NMU to fix this. The debdiff is attached.
diff -Nru mate-equake-applet-1.3.8.2/debian/changelog
mate-equake-applet-1.3.8.2/debian/changelog
--- mate-equake-applet-1.3.8.2/debian/changelog 2018-05-05 04:10:14.000000000
+0200
+++ mate-equake-applet-1.3.8.2/debian/changelog 2023-05-08 19:44:08.000000000
+0200
@@ -1,3 +1,12 @@
+mate-equake-applet (1.3.8.2-1.1) unstable; urgency=medium
+
+ * Non-maintainer upload
+ * Fix lintian: build-depends-on-obsolete-package
+ * Represent the actual gtk3 build dependency that is also available via
+ libmate-panel-applet-dev (Closes: #967626)
+
+ -- Bastian Germann <b...@debian.org> Mon, 08 May 2023 19:44:08 +0200
+
mate-equake-applet (1.3.8.2-1) unstable; urgency=low
* New upstream release (Closes: #849267)
diff -Nru mate-equake-applet-1.3.8.2/debian/control
mate-equake-applet-1.3.8.2/debian/control
--- mate-equake-applet-1.3.8.2/debian/control 2017-03-05 15:06:20.000000000
+0100
+++ mate-equake-applet-1.3.8.2/debian/control 2023-05-08 19:44:08.000000000
+0200
@@ -9,11 +9,11 @@
libcurl4-gnutls-dev,
libatk1.0-dev,
libcairo2-dev,
- libfontconfig1-dev,
- libfreetype6-dev,
- libgdk-pixbuf2.0-dev,
+ libfontconfig-dev,
+ libfreetype-dev,
+ libgdk-pixbuf-2.0-dev,
libglib2.0-dev,
- libgtk2.0-dev,
+ libgtk-3-dev,
libpango1.0-dev,
Standards-Version: 3.9.8
Homepage: https://www.e-quake.org
