Update to egui 0.31 (#22)

Author: emilk

.github/workflows/rust.yml

@@ -27,7 +27,7 @@ jobs:
 
       - name: Install packages (Linux)
         if: runner.os == 'Linux'
-        uses: awalsh128/cache-apt-pkgs-action@v1.3.0
+        uses: awalsh128/cache-apt-pkgs-action@v1.4.3
         with:
           # some deps used by eframe, if that is part of the project
           packages: libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev libxkbcommon-dev libssl-dev # libgtk-3-dev is used by rfd