testing: Use pipx to install swidGenerator on Debian trixie

We could use the same approach on bookworm (if the base image is updated),
but just use the old approach there for now.

testing/scripts/recipes/014_swid_generator.mk

@@ -17,4 +17,8 @@ $(TAR):
 	@touch $@
 
 install: .$(PKG)-unpacked-$(REV)
+ifeq (,$(filter $(BASEIMG),bullseye bookworm))
+	cd $(DIR) && pipx install --global --system-site-packages .
+else
 	cd $(DIR) && SETUPTOOLS_USE_DISTUTILS=stdlib python3 setup.py install
+endif