ci: Add apt-get update

Author: tomsmeding

.github/workflows/ci.yml

@@ -80,6 +80,7 @@ jobs:
             echo CABAL_FLAGS=--enable-tests --test-show-details=direct --flags=nofib >> $GITHUB_ENV
           else
             if [ ${{ matrix.os }} == 'ubuntu-latest' ]; then
+              sudo apt-get update
               sudo apt-get -y install cmake pkg-config libfreetype-dev libglfw3-dev libgtk-3-dev libtbb-dev
             elif [ ${{ matrix.os }} == 'macOS-latest' ]; then
               brew install cmake pkg-config freetype glfw