Skip UI tests in minimal-deps CI as well

This wasn't necessary so far, but it makes sense that different dependency versions can lead to different error messages.
We only run UI tests against one stable Rust version.

Author: Bromeon

.github/workflows/full-ci.yml

@@ -139,6 +139,7 @@ jobs:
             testflags: '-- --skip ui_tests'
           - os: { id: ubuntu-latest, name: linux }
             rust: { toolchain: 'stable', postfix: ' (minimal-deps)', special: 'minimal-deps' }
+            testflags: '-- --skip ui_tests'
     runs-on: ${{ matrix.os.id }}
     steps:
       - uses: actions/checkout@v3