remove signing. I don't think it's necessary

but something else causes SIGKILL on mac until signing, so
something related to that is still wrong

.github/workflows/prebuild.yaml

@@ -180,11 +180,6 @@ jobs:
           brew uninstall --force --ignore-dependencies cairo pango librsvg giflib harfbuzz
           npm test
 
-      - name: Sign the executable
-        uses: indygreg/apple-code-sign-action@v1
-        with:
-          input_path: build/Release/canvas.node
-
       - name: Make bundle
         id: make_bundle
         run: . prebuild/tarball.sh