I am uploading a NMU to DELAyED/10 in order to fix this.
The debdiff is attached.diff -Nru vonsh-1.0/debian/changelog vonsh-1.0/debian/changelog
--- vonsh-1.0/debian/changelog 2019-08-26 13:29:08.0 +0200
+++ vonsh-1.0/debian/changelog 2023-10-23 00:25:29.0 +0200
@@ -1,3 +1,11 @@
+vonsh (1.0-0.1) unstable; urgency=medium
+
+ * Non-maintainer upload.
+ * Drop build-essential packages from Build-Depends. (Closes: #949218)
+ * Convert to source format 3.0. (Closes: #1007398)
+
+ -- Bastian Germann Mon, 23 Oct 2023 00:25:29 +0200
+
vonsh (1.0) unstable; urgency=medium
* Initial packaging. Closes: #935761
diff -Nru vonsh-1.0/debian/control vonsh-1.0/debian/control
--- vonsh-1.0/debian/control2019-08-26 13:29:08.0 +0200
+++ vonsh-1.0/debian/control2023-10-23 00:25:26.0 +0200
@@ -2,7 +2,7 @@
Section: games
Priority: optional
Maintainer: Andrzej Urbaniak
-Build-Depends: libc6-dev (>=2.28), gcc (>=4:8.3.0), g++ (>=4:8.3.0), make
(>=4.2.1), dpkg-dev (>=1.19.7), debhelper (>= 12), libsdl2-dev (>=2.0.9),
libsdl2-image-dev (>=2.0.4), libsdl2-mixer-dev (>=2.0.4)
+Build-Depends: debhelper (>= 12), libsdl2-dev (>=2.0.9), libsdl2-image-dev
(>=2.0.4), libsdl2-mixer-dev (>=2.0.4)
Standards-Version: 4.3.0
Homepage: https://github.com/aurb/vonsh/
diff -Nru vonsh-1.0/debian/source/format vonsh-1.0/debian/source/format
--- vonsh-1.0/debian/source/format 2019-08-23 22:08:14.0 +0200
+++ vonsh-1.0/debian/source/format 2023-10-23 00:25:29.0 +0200
@@ -1 +1 @@
-1.0
+3.0 (quilt)