use new github "inputs" context, where booleans are supposed to actually be booleans

see https://github.com/actions/runner/issues/1483
see https://docs.github.com/en/actions/learn-github-actions/contexts#inputs-context

[ci skip]

.github/workflows/debian.yml

@@ -111,7 +111,7 @@ jobs:
             cryptomator_*_amd64.deb
             cryptomator_*.asc
       - name: Publish on PPA
-        if: startsWith(github.ref, 'refs/tags/') || github.event.inputs.dput == 'true'
+        if: startsWith(github.ref, 'refs/tags/') || inputs.dput
         run: dput ppa:sebastian-stenzel/cryptomator-beta cryptomator_*_source.changes
       - name: Publish Debian package on GitHub Releases
         if: startsWith(github.ref, 'refs/tags/')