CI: Disable cask creation (for now) [skip ci]

[why]
After discussion with
https://github.com/Homebrew/homebrew-cask-fonts/pull/6167#issuecomment-1229152446
I assume we would never use this in CI.

It can be helpful for new fonts, but even then they suggest using the
tools provided (i.e.`font-casker`):
https://github.com/Homebrew/homebrew-cask-fonts/blob/master/CONTRIBUTING.md#automatic-generation

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

.github/workflows/release.yml

@@ -199,6 +199,7 @@ jobs:
         # The casks are not used at the moment, but probably Ryan
         # wanted to push them out somewhere
         id: cask_generate
+        if: false
         run: |
           cd -- "$GITHUB_WORKSPACE/bin/scripts"
           gen=$(./generate-casks.sh "${{ matrix.font }}")
@@ -225,6 +226,7 @@ jobs:
             LICENSE
 
       - name: Upload casks as artifacts
+        if: false
         uses: actions/upload-artifact@v2
         with:
           name: casks