update proof cmd

Author: m4rc1e

Makefile

@@ -33,7 +33,7 @@ test: venv build.stamp
 	. venv/bin/activate; mkdir -p out/ out/fontbakery; fontbakery check-googlefonts -l WARN --succinct --badges out/badges --html out/fontbakery/fontbakery-report.html --ghmarkdown out/fontbakery/fontbakery-report.md $(shell find fonts/ttf -type f)
 
 proof: venv build.stamp
-	. venv/bin/activate; mkdir -p out/ out/proof; gftools gen-html proof $(shell find fonts/variable -type f) -o out/proof
+	. venv/bin/activate; mkdir -p out/ out/proof; diffenator2 proof $(shell find fonts/variable -type f) -o out/proof
 
 images: venv build.stamp $(DRAWBOT_OUTPUT)
 	git add documentation/*.png && git commit -m "Rebuild images" documentation/*.png