remove workflow as currently not supported by deprecated runner image

.github/workflows/rust.yml

@@ -1,26 +0,0 @@
-name: Rust
-
-on:
-  push:
-    branches: [ "master" ]
-  pull_request:
-    branches: [ "master" ]
-
-env:
-  CARGO_TERM_COLOR: always
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v4
-    - name: Install system packages
-      run: sudo apt install -y libgtk-4-dev libglib2.0-dev
-    - name: Set PKG_CONFIG_PATH
-      run: echo "PKG_CONFIG_PATH=/usr/lib/pkgconfig:/usr/share/pkgconfig:/usr/lib/x86_64-linux-gnu/pkgconfig" >> $GITHUB_ENV
-    - name: Build
-      run: cargo build --verbose
-    - name: Run tests
-      run: cargo test --verbose