ci: opensuse: add setuptools

`test_meson_installed` fails without setuptools:
```
$ /usr/bin/python3 run_meson_command_tests.py -v
Meson build system 1.5.99 Command Tests
test_meson_exe_windows (__main__.CommandTests.test_meson_exe_windows) ... skipped 'NOT IMPLEMENTED'
test_meson_installed (__main__.CommandTests.test_meson_installed) ... Traceback (most recent call last):
  File "/meson/setup.py", line 12, in <module>
    from setuptools import setup
ModuleNotFoundError: No module named 'setuptools'
ERROR
```

ci/ciimage/opensuse/install.sh

@@ -5,7 +5,7 @@ set -e
 source /ci/common.sh
 
 pkgs=(
-  python3-pip python3 python3-devel
+  python3-pip python3 python3-devel python3-setuptools
   ninja make git autoconf automake patch libjpeg-devel
   elfutils gcc gcc-c++ gcc-fortran gcc-objc gcc-obj-c++ vala rust bison flex curl lcov
   mono-core gtkmm3-devel gtest gmock protobuf-devel wxGTK3-3_2-devel gobject-introspection-devel